JPWO2009028453A1 - Thin film transistor - Google Patents

Abstract

The present invention provides a thin film transistor having a high on / off ratio that stabilizes a thin film transistor (TFT) element, that is, improves mobility and lowers off current, and provides a thin film transistor with improved production efficiency. The thin film transistor of the present invention has a structure in which a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor are stacked, and the first and second active layers are laminated. To do.

Description

  The present invention relates to a thin film transistor (TFT), and further relates to a thin film transistor composed of an organic active material and an inorganic oxide active material.

  Thin film transistors are well known and research on organic semiconductors is very active.

A TFT having an amphoteric drive characteristic in which an n-type organic semiconductor and a p-type organic semiconductor are stacked in a thin film transistor is known (for example, Patent Documents 1 and 2).
Both have a configuration in which n-type and p-type organic semiconductor layers are stacked, and in the stacked configuration of n-type and p-type organic semiconductor layers, the SD electrode is formed at a position sandwiched between two semiconductor layers. ing.

  These include the reduction of current at zero bias (off current), improvement of carrier mobility, improvement of on / off ratio in a thin film transistor, and p-type channel depending on amphoteric driving characteristics, that is, bias conditions. Alternatively, it is an object of the present invention to be able to be used as any transistor in a complementary circuit related to the prior art by using the characteristics of an n-type channel transistor.

However, in the above-described prior art, not only driving characteristics such as mobility, on / off ratio and threshold value are low, but also durability is a problem.
JP-A-8-228034 JP 2004-235624 A

  Accordingly, an object of the present invention is to provide a thin film transistor having a high on / off ratio that stabilizes a thin film transistor (TFT) element, that is, improves mobility and lowers off current, The object is to provide a thin film transistor that is resistant to high or low humidity and has high durability and improved production efficiency.

  The above object of the present invention is achieved by the following means.

  1. A thin film transistor comprising a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor, wherein the first and second active layers are stacked.

  2. 2. The thin film transistor according to 1 above, wherein a second active layer is formed on the first active layer.

  3. 3. The thin film transistor according to 1 or 2 above, wherein the surface of the first active layer is subjected to a surface treatment with an organic substance.

  4). 4. The thin film transistor according to any one of 1 to 3, wherein at least the second active layer is formed by casting from a solution.

  5. 5. The thin film transistor according to any one of items 1 to 4, wherein the first active layer is formed by a process including casting from a solution.

  6). 6. The thin film transistor according to any one of 1 to 5, wherein the thin film transistor exhibits driving characteristics of both n-type channel operation and p-type channel operation.

  7). 7. The thin film transistor according to any one of 1 to 6, wherein the second active layer is a p-type semiconductor.

  8). 8. The thin film transistor according to any one of 1 to 7, wherein the first active layer made of a metal oxide semiconductor contains any one of In, Zn, and Sn.

  9. 9. The thin film transistor according to any one of 1 to 8, wherein the first active layer made of a metal oxide semiconductor contains Ga and Al.

  10. 10. The thin film transistor according to any one of 1 to 9, wherein the second active layer made of an organic semiconductor contains a compound represented by the following general formula (OSC1).

(Wherein R _{1 to} R ₆ represent a hydrogen atom or a substituent, Z ₁ or Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocyclic ring, n1 or n2 represents an integer of 0 to 3.)
11. 11. The thin film transistor according to any one of 1 to 10, wherein the first active layer is in contact with a source and a drain by a top contact type configuration.

  According to the present invention, a highly durable thin film transistor with improved driving characteristics such as mobility, on / off ratio, and threshold can be obtained.

It is the schematic which shows an example of an ultrasonic atomizer. It is the schematic which shows an example of a single wafer type atmospheric pressure plasma processing apparatus. It is the schematic which shows an example of a roll-type atmospheric pressure plasma processing apparatus. It is a cross-sectional schematic diagram which shows the structural example of the thin-film transistor of this invention. 1 is a schematic equivalent circuit diagram of an example of a thin film transistor sheet in which a plurality of thin film transistor elements of the present invention are arranged. It is the figure which showed typically the gate voltage-drain current characteristic of the thin-film transistor of this invention. It is a schematic cross-sectional schematic diagram of an example of the manufacturing process of a thin-film transistor sheet. It is a schematic equivalent circuit diagram which shows an example of the manufacturing process of a thin-film transistor sheet. It is a schematic equivalent circuit diagram which shows an example of the manufacturing process of a thin-film transistor sheet. It is a schematic equivalent circuit diagram which shows an example of the manufacturing process of a thin-film transistor sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic sprayer 11 Introducing pipe 12 Raw material storage part 13 Ultrasonic wave generation part 14 Power supply 15 Release pipe 21 1st electrode 22, 32 2nd electrode 22R, 35 Roll rotation electrode 25A, 25B High frequency power supply 26A, 26B Matching box 27A, 27B Filter 30 Atmospheric pressure plasma processing apparatus 101 Substrate 102 Gate electrode 103 Gate insulating layer 104 First active layer 106 Second active layer 105 Source / drain electrode 105a Source electrode 105b Drain electrode 120 Thin film transistor sheet 121 Gate bus line 122 Source bus line 124 Thin film transistor element 125 Storage capacitor 126 Output element 127 Vertical drive circuit 128 Horizontal drive circuit

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  In order to achieve the above-described object, a thin film transistor of the present invention has a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor, and the first and second active layers are It has a laminated structure.

  That is, a field effect comprising a channel region, a source electrode and a drain electrode arranged to face each other through the channel region, an insulating layer covering at least the channel region, and a gate electrode formed on the insulating layer on the channel In a type transistor, a channel region formed between a source electrode and a drain electrode has a structure in which a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor are stacked.

  The thin film transistor of the present invention is an organic / inorganic hybrid semiconductor material composed of a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor.

  In the present invention, the first active layer made of a metal oxide semiconductor and the second active layer made of an organic semiconductor may each be a single semiconductor material, or two or more organic semiconductors of the same conductivity type. It may be formed from a material.

The electron mobility of the semiconductor in the first active layer made of the metal oxide semiconductor is preferably 10 ⁻³ cm ² / V · s or more, and in the second active layer made of the organic semiconductor of the present invention. The hole mobility of the semiconductor is preferably 10 ⁻³ cm ² / V · s or more.

  Although there is no restriction | limiting in the metal oxide semiconductor used in this invention, It is preferable that it is an n-type semiconductor material, and it can produce it by well-known processes, such as a sputtering, After providing the thin film, it is preferable to obtain a metal oxide semiconductor thin film by oxidizing the thin film by thermal oxidation, plasma oxidation, or light irradiation in the presence of oxygen.

  In the present invention, the first active layer made of a metal oxide semiconductor is formed by forming a thin film containing a material that is a precursor of the metal oxide semiconductor, and then oxidizing the formed thin film. To form. As a thin film oxidation treatment method, a thermal oxidation method, a plasma oxidation method, a UV ozone method, or the like can be used.

  Examples of the metal oxide semiconductor precursor include metal salts, metal halides, and organometallic compounds containing metal atoms.

  Metal oxides, metal salts, metal halides, organometallic compounds, metal hydride metals include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Ir, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl , Pb, Bi, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and the like.

  Among these metal salts, it is preferable to contain any of indium, tin, and zinc, and they may be used in combination. Moreover, it is preferable that a gallium or aluminum is included as another metal.

  As metal salts, nitrates, acetates and the like can be suitably used, and as halides, chlorides, iodides, bromides and the like can be suitably used.

  Examples of the organometallic compound include those represented by the following general formula (I).

Formula (I) R ¹ _x MR ² _y R ³ _z
In the formula, M is a metal, R ¹ is an alkyl group, R ² is an alkoxy group, R ³ is a β-diketone complex group, a β-ketocarboxylic acid ester complex group, a β-ketocarboxylic acid complex group, and a ketooxy group (ketooxy complex group). X + y + z = m, x = 0 to m, or x = 0 to m−1, and y = 0 to m, z = 0. ~ M, each of which is 0 or a positive integer. Examples of the alkyl group for R ¹ include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group for R ² include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a 3,3,3-trifluoropropoxy group. Moreover, the hydrogen atom of the alkyl group may be substituted with a fluorine atom. Examples of the group selected from the β-diketone complex group, the β-ketocarboxylic acid ester complex group, the β-ketocarboxylic acid complex group, and the ketooxy group (ketooxy complex group) of R ³ include, for example, 2,4 -Pentanedione (also called acetylacetone or acetoacetone), 1,1,1,5,5,5-hexamethyl-2,4-pentanedione, 2,2,6,6-tetramethyl-3,5-heptanedione , 1,1,1-trifluoro-2,4-pentanedione and the like, as the β-ketocarboxylic acid ester complex group, for example, acetoacetic acid methyl ester, acetoacetic acid ethyl ester, acetoacetic acid propyl ester, trimethylacetate Examples thereof include ethyl acetate, methyl trifluoroacetoacetate and the like. As β-ketocarboxylic acid, For example, acetoacetic acid, trimethylacetoacetic acid and the like can be mentioned, and examples of ketooxy include acetooxy group (or acetoxy group), propionyloxy group, butyryloxy group, acryloyloxy group, methacryloyloxy group and the like. These groups preferably have 18 or less carbon atoms. Further, it may be linear or branched, or a hydrogen atom may be a fluorine atom. Among organometallic compounds, those having at least one oxygen in the molecule are preferable. As such, an organometallic compound containing at least one alkoxy group of R ² , a β-diketone complex group, a β-ketocarboxylic acid ester complex group, a β-ketocarboxylic acid complex group and a ketooxy group (ketooxy group) of R ³ Most preferred are metal compounds having at least one group selected from (complex groups). Among the metal salts, nitrate is preferable. Nitrate is easily available as a high-purity product and has high solubility in water, which is preferable as a medium for use. Examples of nitrates include indium nitrate, tin nitrate, zinc nitrate, and gallium nitrate.

  As a thin film forming material used for forming the semiconductor film of the present invention, a metal atom-containing compound is preferable. Examples of the metal atom-containing compound include metal salts, organometallic compounds, halogen metal compounds, metal hydride compounds, and the like. Particularly preferred organometallic compounds include the metal compounds represented by the general formula (I). Can be mentioned.

  Of the above precursors, metal nitrates, halides, and alkoxides are preferable. Specific examples include indium nitrate, zinc nitrate, gallium nitrate, tin nitrate, aluminum nitrate, indium chloride, zinc chloride, tin chloride (divalent), tin chloride (tetravalent), gallium chloride, aluminum chloride, tri-i-. Examples include propoxyindium, diethoxyzinc, bis (dipivaloylmethanato) zinc, tetraethoxytin, tetra-i-propoxytin, tri-i-propoxygallium, and tri-i-propoxyaluminum.

(Film formation method, patterning method)
As a method for forming the precursor thin film, it is preferable to form the thin film by coating a solution of the precursor and casting the solvent.

  Solvents include water, alcohols such as ethanol, propanol and ethylene glycol, ethers such as tetrahydrofuran and dioxane, esters such as methyl acetate and ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, diethylene glycol monomethyl ether, etc. Glycol ethers, acetonitrile, and other aromatic hydrocarbon solvents such as xylene and toluene, aromatic solvents such as o-dichlorobenzene, nitrobenzene, and m-cresol, aliphatic carbonization such as hexane, cyclohexane, and tridecane Hydrogen solvents, α-terpineol, alkyl halide solvents such as chloroform and 1,2-dichloroethane, N-methylpyrrolidone, carbon disulfide and the like can be suitably used. Alcohols such as ethanol and, also, such as acetonitrile, can be used any as long as it is a solvent which can dissolve the precursor.

  In the present invention, as a method of forming a thin film containing a metal oxide semiconductor precursor by applying a liquid containing a thin film forming material on a substrate, a spray coating method, a spin coating method, a blade coating method, Examples thereof include a dip coating method, a cast method, a roll coating method, a bar coating method, a die coating method, and a mist method, and a patterning method using a printing method such as a relief plate, an intaglio plate, a planographic printing method, a screen printing method, and an ink jet method. The coating film may be patterned by photolithography, laser ablation, or the like. Conventionally known methods can be applied to the formation and patterning of a thin film containing metal fine particles. Of these, the spray coating and mist methods that can apply a thin film are preferable.

  A preferred droplet forming method in the mist method will be described below.

  FIG. 1 is a schematic view of an ultrasonic sprayer used when a liquid containing a thin film forming material is applied as droplets on a substrate or supplied between electrodes. Thereby, a micro droplet (droplet) can be formed. In FIG. 1, 1 is an ultrasonic atomizer, 11 is an introduction tube for introducing nitrogen gas, 12 is a raw material reservoir for storing a liquid L containing a thin film forming material as a droplet raw material, 13 is an ultrasonic generator, 14 Is a power source connected to the ultrasonic wave generator 13, and 15 is a discharge tube for discharging the generated droplets. When nitrogen gas is introduced from the introduction pipe 11 into the raw material storage unit 12 and the power source 14 is turned on to generate ultrasonic waves from the ultrasonic wave generation unit 13, droplets are generated. The droplets generated in this way are discharged to the outside of the ultrasonic sprayer 1 through the discharge tube 15, and the droplets are sprayed onto the substrate at an appropriate location of an atmospheric pressure plasma apparatus (not shown). Plasma oxidation is performed on the thin film to be formed in the atmospheric pressure plasma processing apparatus.

  FIG. 2 is a schematic diagram of a single-wafer type atmospheric pressure plasma processing apparatus equipped with an ultrasonic atomizer, whereby thin film formation by droplet spraying and plasma oxidation by atmospheric pressure plasma processing can be performed continuously or simultaneously. . In FIG. 2, reference numeral 1 denotes an ultrasonic sprayer similar to that shown in FIG. The droplets M sprayed downward from the ultrasonic sprayer 1 are applied onto the substrate S in the spray space A. Reference numeral 21 denotes a fixed first electrode, and reference numeral 22 denotes a second electrode that supports the substrate S and can be repeatedly moved in the direction of the arrow in the figure. The first electrode 21 and the second electrode 22 are provided to face each other with a predetermined gap, and this gap constitutes the discharge space D. The first electrode 21 and the second electrode 22 are connected to a filter 27A or 27B, which is a load, a matching box 26A or 26B, and a high-frequency power source 25A or 25B, respectively, and are grounded. The filter is inserted in order to superimpose two different types of high-frequency electric fields in the discharge space so that the high-frequency waves do not affect each other's power supply. The matching box is inserted to cancel the reactance component of the load and correct the impedance in order to effectively use the energy of the high-frequency power source.

  The first high-frequency electric field generated by the high-frequency power supply 25A and the second high-frequency electric field generated by the high-frequency power supply 25B satisfy the following relationship. The frequency ω2 of the second high-frequency electric field is higher than the frequency ω1 of the first high-frequency electric field, and the strength V1 of the first high-frequency electric field, the strength V2 of the second high-frequency electric field, and the strength of the discharge start electric field The relationship with IV satisfies V1 ≧ IV> V2 or V1> IV ≧ V2. As described above, by superimposing two types of high-frequency electric fields satisfying this relationship, a stable and high-density discharge state can be achieved even when a gas such as nitrogen having a high discharge starting electric field strength is used. High-quality film formation can be performed.

  For example, a high frequency with a frequency of 100 kHz is used as the first high frequency electric field, and a high frequency with a frequency of 13.56 MHz is used as the second high frequency electric field facing the first high frequency electric field. Between the electrodes, for example, a mixed gas of 0.1% by volume of oxygen gas is introduced into the nitrogen gas to form a discharge space.

  The substrate S such as glass is placed on the second electrode 22 and repeatedly moves between the spray space A and the discharge space D. In the spray space A, liquid droplets containing the thin film forming material are applied onto the substrate S. In the discharge space D, a discharge gas such as nitrogen is supplied, two kinds of high-frequency electric fields are superimposed, and high-density plasma is generated, and the substrate S to which droplets are applied is exposed. Plasma processing is performed by repeating this.

  FIG. 3 is also a schematic view of a roll-type atmospheric pressure plasma processing apparatus provided with an ultrasonic atomizer. In FIG. 3, the same reference numerals as those in FIG. 2 are the same as the members described in FIG. In FIG. 3, S is a long base material such as a plastic film. The base material S is wound around the roll electrode 22R that is the second electrode, and is conveyed in the direction of the arrow in the drawing. The droplet M containing the thin film forming material sprayed from the ultrasonic sprayer 1 is applied on the substrate S in the spray space A. Thereafter, when the base material S to which the droplet M is applied passes through the discharge space D formed between the first electrode 21 and the second electrode 22R, a thin film is formed.

As the first power supply (high frequency power supply) installed in the atmospheric pressure plasma processing apparatus,
Applied power symbol Manufacturer Frequency Product name A1 Shinko Electric 3kHz SPG3-4500
A2 Shinko Electric 5kHz SPG5-4500
A3 Kasuga Electric 15kHz AGI-023
A4 Shinko Electric 50kHz SPG50-4500
A5 HEIDEN Research Laboratories 100kHz * PHF-6k
A6 Pearl Industry 200kHz CF-2000-200k
A7 Pearl Industry 400kHz CF-2000-400k
And the like, and any of them can be used.

As the second power source (high frequency power source),
Applied power supply symbol Manufacturer Frequency Product name B1 Pearl Industry 800kHz CF-2000-800k
B2 Pearl Industry 2MHz CF-2000-2M
B3 Pearl Industry 13.56MHz CF-5000-13M
B4 Pearl Industry 27MHz CF-2000-27M
B5 Pearl Industry 150MHz CF-2000-150M
And the like, and any of them can be preferably used.

  Of the above power supplies, * indicates a HEIDEN Laboratory impulse high-frequency power supply (100 kHz in continuous mode). Other than that, it is a high-frequency power source that can apply only a continuous sine wave.

In the present invention, the power applied between the electrodes facing each other supplies power (power density) of 1 W / cm ² or more to the second electrode (second high-frequency electric field) to excite the discharge gas to generate plasma. , Energy is applied to the thin film-forming droplet, and plasma oxidation is performed. The upper limit value of the power supplied to the second electrode is preferably 50 W / cm ² , more preferably 20 W / cm ² . The lower limit is preferably 1.2 W / cm ² . In addition, discharge area (cm < ² >) points out the area of the range which discharge occurs in an electrode.

Further, by supplying power (output density) of 1 W / cm ² or more to the first electrode (first high frequency electric field), the output density is improved while maintaining the uniformity of the second high frequency electric field. be able to. Thereby, a further uniform high-density plasma can be generated, and a further improvement in film forming speed and an improvement in film quality can be achieved. Preferably it is 5 W / cm ² or more. The upper limit value of the power supplied to the first electrode is preferably 50 W / cm ² .

  Here, the waveform of the high-frequency electric field is not particularly limited. There are a continuous sine wave continuous oscillation mode called a continuous mode, an intermittent oscillation mode called ON / OFF intermittently called a pulse mode, and either of them may be adopted, but at least the second electrode side (second The high-frequency electric field is preferably a continuous sine wave because a denser and better quality film can be obtained.

  Accordingly, the liquid containing the thin film forming material is preferably applied as droplets by spraying or the like on the substrate. The average particle size of the droplets is 5 μm or less, preferably 1 μm or less. The average particle size of the droplets can be measured by simply irradiating the droplet group with laser light and calculating the particle size distribution from the intensity distribution pattern of the diffracted / scattered light emitted from it. The company's LDSA-1500A can be used.

  In this invention, after forming the thin film containing the metal used as the precursor of a metal oxide semiconductor in this way, a metal oxide semiconductor is manufactured by performing plasma oxidation with respect to this thin film.

  As a method for oxidizing a thin film formed of a metal material which is a precursor of a metal oxide semiconductor, it is preferable to use plasma oxidation as described above in the present invention.

  As the plasma oxidation, an atmospheric pressure plasma method using the atmospheric pressure plasma processing apparatus is preferable. In plasma oxidation, the substrate on which the thin film containing the precursor is formed is preferably heated in the range of 150 ° C to 300 ° C.

  In the atmospheric pressure plasma method, an inert gas such as argon gas or nitrogen gas is used as a discharge gas under atmospheric pressure, and a reactive gas (a gas containing oxygen) is introduced into the discharge space and a high frequency electric field is applied. The plasma oxidation is performed by exciting the discharge gas, generating plasma, bringing it into contact with the reaction gas, generating oxygen plasma, and exposing the substrate surface to this. Under atmospheric pressure represents a pressure of 20 to 110 kPa, preferably 93 to 104 kPa.

  When an oxygen plasma is generated using a gas containing oxygen as a reactive gas by the atmospheric pressure plasma method, the gas to be used varies depending on the type of thin film, but basically a discharge gas (inert gas) and an oxidizing gas. It is a mixed gas. When performing plasma oxidation, it is preferable to contain 0.01-10 volume% of oxygen gas with respect to mixed gas as oxidizing gas. Although it is more preferable that it is 0.1-10 volume%, More preferably, it is 0.1-5 volume%.

  Examples of the inert gas include Group 18 elements of the periodic table, specifically, helium, neon, argon, krypton, xenon, radon, nitrogen gas, etc., in order to obtain the effects described in the present invention. For this, helium, argon, or nitrogen gas is preferably used.

  In order to introduce the reaction gas between the electrodes which are the discharge space, normal temperature and normal pressure may be used.

  The plasma method under atmospheric pressure is described in JP-A-11-61406, JP-A-11-133205, JP-A-2000-121804, JP-A-2000-147209, JP-A-2000-185362, WO2006 / 129461, and the like.

  In the plasma oxidation, it is preferable to heat the substrate in the range of 150 ° C. to 300 ° C.

(Oxide semiconductor thin film)
By the method of the present invention, a metal oxide semiconductor thin film containing a single metal atom or a plurality of metal atoms selected from the metal atoms described above is produced. As the metal oxide semiconductor, any state of single crystal, polycrystal, and amorphous can be used, but an amorphous thin film is preferably used.

  The metal atom contained in the formed metal oxide semiconductor preferably contains any of indium, tin, and zinc, and further preferably contains gallium or aluminum, as described in the description of the precursor.

As a preferable composition ratio, when In is 1, Zn _y Sn _1-y (where y is a positive number from 0 to ₁ ) is preferably 0.2 to 5, more preferably 0.5 to 2. is there. Moreover, when In is set to 1, the composition ratio of Ga or Al is preferably 0 to 5, and more preferably 0.5 to 2.

  The film thickness of the semiconductor thin film is preferably 1 to 200 nm, more preferably 5 to 100 nm.

  The film thickness of the semiconductor that is a metal oxide is not particularly limited, but the characteristics of the obtained transistor are often greatly influenced by the film thickness of the semiconductor film, and the film thickness varies depending on the semiconductor. Generally, 1 μm or less, particularly 10 to 300 nm is preferable.

In the present invention, in the plasma oxidation, the precursor material and the composition ratio, the gas composition ratio in the plasma oxidation, the flow rate, the electrode conditions (frequency, potential, etc.) are controlled to control, for example, the electron carrier concentration. Is 10 ¹² / cm ³ or more and less than 10 ¹⁸ / cm ³ . More preferably, it is in the range of 10 ¹³ / cm ³ or more and 10 ¹⁷ / cm ³ or less, and more preferably 10 ¹⁵ / cm ³ or more and 10 ¹⁶ / cm ³ or less.

  The electron carrier concentration can be measured by Hall effect measurement.

(Thin film oxidation process)
As a method for oxidizing a thin film formed of a metal material which is a precursor of a metal oxide semiconductor, a thermal oxidation method, a UV ozone method, or the like can be used in addition to the plasma oxidation method. The UV ozone method is a method of irradiating ultraviolet light in the presence of oxygen to advance an oxidation reaction. It is preferable to irradiate so-called vacuum ultraviolet light having a wavelength of ultraviolet light of 100 nm to 450 nm, particularly preferably about 150 to 300 nm. As the light source, a low-pressure mercury lamp, a deuterium lamp, a xenon excimer lamp, a metal halide lamp, an excimer laser, or the like can be used. It is preferable to heat the substrate in the range of 50 ° C to 400 ° C, preferably 100 ° C to 250 ° C.

(Metal oxide semiconductor)
By the method of the present invention, a thin film of a metal oxide semiconductor containing a single metal atom or a plurality of metal atoms selected from the metal atoms described above can be produced. As the metal oxide semiconductor, any state of single crystal, polycrystal, and amorphous can be used, but an amorphous thin film is preferably used.

The metal atom contained in the formed metal oxide semiconductor preferably contains any of indium, tin, and zinc, and further preferably contains gallium or aluminum, as described in the description of the precursor. As a preferable composition ratio, when In is 1, Zn _y Sn _1-y (where y is a positive number from 0 to ₁ ) is preferably 0.2 to 5, more preferably 0.5 to 2. is there. When In is 1, the composition ratio of Ga and / or Al is preferably 0 to 5, and more preferably 0.5 to 2.

  The film thickness of the semiconductor that is a metal oxide is not particularly limited, but the characteristics of the obtained transistor are often greatly influenced by the film thickness of the semiconductor film, and the film thickness varies depending on the semiconductor. In general, it is 1 μm or less, particularly preferably 1 to 300 nm, more preferably 5 to 200 nm, still more preferably 10 to 100 nm.

In the present invention, for example, in the plasma oxidation, for example, the precursor material and the composition ratio, the gas composition ratio in the plasma oxidation, the flow rate, the electrode conditions (frequency, potential, etc.) are controlled, and for example, The electron carrier concentration is set to 10 ¹² / cm ³ or more and less than 10 ¹⁸ / cm 3. More preferably, it is in the range of 10 ¹³ / cm ³ or more and 10 ¹⁷ / cm ³ or less, and more preferably 10 ¹⁵ / cm ³ or more and 10 ¹⁶ / cm ³ or less.

  The electron carrier concentration can be measured by Hall effect measurement.

  These metal oxide semiconductor thin films can be used as the first active layer of the field effect transistor (thin film transistor: TFT) according to the present invention.

(Organic semiconductor thin film: Organic semiconductor layer)
The second active layer made of an organic semiconductor is preferably a p-type semiconductor, that is, a semiconductor that transmits positive charge carriers more efficiently than negative charge carriers, and the charge carriers (carriers) are generally holes. It is.

  In this specification, a p-type (n-type) semiconductor refers to a semiconductor that transmits (does not transmit) positive charge carriers more efficiently than negative charge carriers. Positive (negative) charge carriers (carriers) Is called a hole (electron).

  In the present invention, as the organic semiconductor material constituting the second active layer, various condensed polycyclic aromatic compounds and conjugated compounds described later can be applied.

  Examples of the condensed polycyclic aromatic compound as the organic semiconductor material include, for example, anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, circumcamanthracene, Examples thereof include compounds such as bisanthene, zestrene, heptazeslen, pyranthrene, violanthene, isoviolanthene, cacobiphenyl, phthalocyanine, porphyrin, and derivatives thereof.

  Examples of the conjugated compound include polythiophene and its oligomer, polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, tetrathiafulvalene compound, quinone Compounds, cyano compounds such as tetracyanoquinodimethane, fullerenes and derivatives or mixtures thereof.

  In particular, among polythiophene and oligomers thereof, thiophene hexamer α-seccithiophene α, ω-dihexyl-α-sexithiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3- Butoxypropyl) -α-secthiothiophene and oligomers such as the following compounds can be preferably used.

  Furthermore, metal phthalocyanines such as copper phthalocyanine and fluorine-substituted copper phthalocyanine described in JP-A No. 11-251601, naphthalene 1,4,5,8-tetracarboxylic acid diimide, N, N′-bis (4-trifluoromethylbenzyl) Along with naphthalene 1,4,5,8-tetracarboxylic acid diimide, N, N'-bis (1H, 1H-perfluorooctyl), N, N'-bis (1H, 1H-perfluorobutyl) and N, N'- Dioctylnaphthalene 1,4,5,8-tetracarboxylic acid diimide derivatives, naphthalene 2,3,6,7 tetracarboxylic acid diimides and other naphthalene tetracarboxylic acid diimides, and anthracene 2,3,6,7-tetracarboxylic acid Anthracene tetracarboxylic acid diimides such as diimide Bon acid diimides, C60, C70, C76, C78, C84 etc. fullerenes, carbon nanotubes, merocyanine dyes, such as SWNT, and the like pigments such hemicyanine dyes.

  Among these π-conjugated materials, at least one selected from the group consisting of condensed polycyclic aromatic compounds such as pentacene, fullerenes, condensed ring tetracarboxylic acid diimides, and metal phthalocyanines is preferable.

  Other organic semiconductor materials include tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTTF-iodine complex, TCNQ-iodine complex. Organic molecular complexes such as can also be used. Furthermore, (sigma) conjugated polymers, such as polysilane and polygermane, and organic-inorganic hybrid material as described in Unexamined-Japanese-Patent No. 2000-260999 can also be used.

  As the organic semiconductor material, a compound represented by the following general formula (OSC1) is preferable.

In the formula, R _{1 to} R ₆ represent a hydrogen atom or a substituent, Z ₁ or Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocyclic ring, and n1 or n2 Represents an integer of 0 to 3.

In the general formula (OSC1), examples of the substituent represented by each of R _{1 to} R ₆ include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, and a tert-pentyl group). Group, hexyl group, octyl group, tert-octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, for example) Allyl group, 1-propenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, isopropenyl group, etc.), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (Also called aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, Cytyl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (also called heteroaryl group, For example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-triazol-1-yl group, 1,2,3- Triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group , Indolyl group, carbazoli Group, carbolinyl group, diazacarbazolyl group (in which one of carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group Etc.), heterocyclic groups (for example, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy groups (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, Dodecyloxy group etc.), cycloalkoxy group (eg cyclopentyloxy group, cyclohexyloxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group) , Pentyl Thio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyl Oxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, Aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylamino Sulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, Octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group) Group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonyl) Nylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group ( For example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylamino Carbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido) Group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, Butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl) Group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthyl) Sulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino) Group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl) Group), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), and the like.

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

In the general formula (OSC1), the aromatic hydrocarbon group or aromatic heterocyclic group represented by Z ₁ or Z ₂ is an aromatic carbon group described as a substituent represented by each of R _{1 to} R ₆ above. It is synonymous with a hydrogen group and an aromatic heterocyclic group, respectively.

  Furthermore, a compound represented by the following general formula (OSC2) is preferable.

(Wherein R ₇ or R ₈ represents a hydrogen atom or a substituent, Z ₁ or Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocyclic ring, and n1 or n2 represents an integer of 0 to 3.)
In the general formula (OSC2), the substituent represented by R ⁷ or R ⁸ has the same meaning as the substituents represented by R _{1 to} R ₆ in the general formula (OSC1). Moreover, the aromatic hydrocarbon group and aromatic heterocyclic group represented by Z ₁ or Z ₂ are the aromatic hydrocarbon groups and aromatics described as the substituents represented by R _{1 to} R ₆ , respectively. Each has the same meaning as a heterocyclic group.

In the general formula (OSC2), the substituents R ₇ — and R ₈ — are preferably represented by the general formula (SG1).

(Wherein R _{9 to} R ₁₁ represent a substituent, and X represents silicon (Si), germanium (Ge), or tin (Sn)).
In the general formula (SG1), the substituent represented by R _{9 to} R ₁₁ has the same meaning as the substituent represented by R _{1 to} R ₃ in the general formula (1).

  Specific examples of the compound represented by the general formula (OSC2) are shown below, but are not limited thereto.

  Examples of organic semiconductor materials include J. Org. Am. Chem. Soc. 2006, 128, 12604, J. Am. Am. Chem. Soc. The compounds described in 2007, 129, 2224, Liquid Crystals 2003, 30, 603-610 can be used.

  In the present invention, for example, a material having a functional group such as acrylic acid, acetamide, dimethylamino group, cyano group, carboxyl group, nitro group, benzoquinone derivative, tetracyanoethylene, and tetracyanoquino Materials that accept electrons, such as dimethane and derivatives thereof, materials having functional groups such as amino group, triphenyl group, alkyl group, hydroxyl group, alkoxy group, phenyl group, phenylenediamine, etc. Including substituted amines, anthracene, benzoanthracene, substituted benzoanthracenes, pyrene, substituted pyrene, carbazole and derivatives thereof, tetrathiafulvalene and derivatives thereof, and the like materials that serve as donors of electrons, So-called doping treatment It may be.

  The doping means introducing an electron-donating molecule (acceptor) or an electron-donating molecule (donor) into the thin film as a dopant. Therefore, the doped thin film is a thin film containing the condensed polycyclic aromatic compound and the dopant. A well-known thing can be employ | adopted as a dopant used for this invention.

  As a method of forming these organic semiconductor layers, it can be formed by a known method, for example, vacuum deposition, MBE (Molecular Beam Epitaxy), ion cluster beam method, low energy ion beam method, ion plating method, Sputtering method, CVD (Chemical Vapor Deposition), laser deposition, electron beam deposition, electrodeposition, casting from solution, spin coating, dip coating, bar coating method, die coating method, spray coating method, LB method, etc. Examples include screen printing, ink jet printing, blade coating, and the like.

  Among these, the spin coating method, blade coating method, dip coating method, roll coating method, bar coating method, die coating method and the like that can form a thin film easily and precisely using an organic semiconductor solution are preferred in terms of productivity. . In particular, when the organic semiconductor layer is formed by the pattern forming method according to the present invention, it is preferable to apply and apply the organic semiconductor solution to the patterned substrate surface.

  The organic solvent used in preparing the organic semiconductor solution is preferably an aromatic hydrocarbon, an aromatic halogenated hydrocarbon, an aliphatic hydrocarbon or an aliphatic halogenated hydrocarbon, an aromatic hydrocarbon, an aromatic halogenated More preferred are hydrocarbons or aliphatic hydrocarbons.

  Examples of the aromatic hydrocarbon organic solvent include toluene, xylene, mesitylene, and methylnaphthalene, but the present invention is not limited thereto.

  Aliphatic hydrocarbons include octane, 4-methylheptane, 2-methylheptane, 3-methylheptane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethyl. Although hexanecyclohexane, cyclopentane, methylcyclohexane, etc. can be mentioned, this invention is not limited to these.

  Examples of the organic solvent for the aliphatic halogenated hydrocarbon include chloroform, bromoform, dichloromethane, dichloroethane, trichloroethane, difluoroethane, fluorochloroethane, chloropropane, dichloropropane, chloropentane, and chlorohexane. It is not limited to these.

  These organic solvents used in the present invention may be used alone or in combination of two or more. The organic solvent preferably has a boiling point of 50 ° C to 250 ° C.

  In addition, as described in Advanced Material 1999 No. 6, p. 480 to 483, a precursor such as pentacene is soluble in a solvent, a target organic material formed by heat treatment of a precursor film formed by coating A thin film may be formed.

  The film thickness of these organic semiconductor layers is not particularly limited, but the characteristics of the obtained transistor are often greatly influenced by the film thickness of the organic semiconductor layer, and the film thickness varies depending on the organic semiconductor. Generally, 1 μm or less, particularly 10 to 300 nm is preferable.

  Furthermore, according to the organic semiconductor device of the present invention, at least one of the gate electrode and the source / drain electrode is formed by the method of manufacturing an organic semiconductor device of the present invention, whereby the low resistance electrode is formed into the organic semiconductor layer. It is possible to form the material layer without causing deterioration of the characteristics of the material layer.

  The surface of the substrate on which the layer made of the organic semiconductor as the second active layer is formed on the first active layer is preferably subjected to a surface treatment made of an organic substance.

  As the surface treatment composed of an organic substance, it is preferable to form a monomolecular film on the surface of the metal oxide as the first active layer by physical adsorption or chemical adsorption, and a surfactant or the like can also be used. The treatment with a silane coupling agent is preferred.

  Especially with silane coupling agents such as octyltrichlorosilane, octadecyltrichlorosilane, phenyltrichlorosilane, octyltriethoxysilane, silazanes such as hexamethyldisilazane, and titanium coupling agents such as octyltrichlorotitanium and octyltriisopropoxytitanium. Surface treatment is preferred.

  These organic substances are preferably bonded on the first active layer to form a layer called a self-assembled film or a monomolecular film. Preferable materials include n-alkylsilanes such as octyltrichlorosilane and octyltriethoxysilane, and silazanes such as hexamethoxydisilazane.

  Moreover, the compound represented by following General formula (1) is also mentioned preferably.

In the general formula (1), X represents any atom selected from silicon, germanium, tin, and lead, and Z represents silicon (Si), titanium (Ti), germanium (Ge), tin (Sn). And any atom selected from lead (Pb). R _{1 to} R ₆ each represent a hydrogen atom or a substituent. Y represents a linking group.

In the general formula (1), examples of the substituent represented by R _{1 to} R ₃ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group). Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group) , Propargyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group) , Pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic ring (Eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), Cycloalkoxyl group (for example, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group) Octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, Methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (For example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl Group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group) Cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy) Group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexyl group) Carbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group Naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylamino) Carbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group) , Dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group) Ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group) Group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group etc.), amino group (for example, amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2- Pyridylamino groups, etc.), halogen atoms (eg, fluorine atoms, chlorine atoms, bromine atoms, etc.), fluorinated hydrocarbon groups (eg, fluoromethyl groups, trifluoromethyl groups, pentafluoroethyl groups, pentafluorophenyl groups, etc.), And cyano group, nitro group, hydroxyl group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

  Of the above substituents, an alkyl group is particularly preferable, and specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a tert-butyl group.

In addition, said various substituents may be further substituted by said substituent. R ₁ , R ₂ and R ₃ may be the same as or different from each other.

  Of the metal atoms represented by X, Si and Ge are preferable.

Examples of the linking group represented by Y include an alkylene group (for example, ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group, 2,2,4-trimethylhexamethylene group). , Heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, cyclohexylene group (for example, 1,6-cyclohexanediyl group, etc.), cyclopentylene group (for example, 1,5 -Cyclopentanediyl group etc.), alkenylene group (eg vinylene group, propenylene group etc.), alkynylene group (eg ethynylene group, 3-pentynylene group etc.), hydrocarbon group such as arylene group, hetero atom (For example, 2 containing a chalcogen atom such as —O— or —S—) Groups, -N (R) - group, where, R represents a hydrogen atom or an alkyl group, the alkyl group in the general formula _(1), the alkyl group represented by R 1 to R ₃ And the like).

  In each of the alkylene group, alkenylene group, alkynylene group, and arylene group, at least one of carbon atoms constituting the divalent linking group is a chalcogen atom (oxygen, sulfur, etc.) or -N (R). -It may be substituted with a group or the like.

  Furthermore, as the linking group represented by Y, for example, a group having a divalent heterocyclic group is used. For example, an oxazolediyl group, a pyrimidinediyl group, a pyridazinediyl group, a pyrandiyl group, a pyrrolinediyl group, an imidazolinediyl group. Group, imidazolidinediyl group, pyrazolidinediyl group, pyrazolinediyl group, piperidinediyl group, piperazinediyl group, morpholinediyl group, quinuclidinediyl group and the like, and thiophene-2,5-diyl group, It may be a divalent linking group derived from a compound having an aromatic heterocycle (also referred to as a heteroaromatic compound) such as a pyrazine-2,3-diyl group.

  Further, it may be a group that meets and links heteroatoms such as an alkylimino group, a dialkylsilanediyl group, or a diarylgermandiyl group.

  Of the above linking groups, preferred are hydrocarbon linking groups such as an alkylene group, an alkenylene group, an alkynylene group, and an arylene group.

  In the general formula (1), among the atoms represented by Z, Si and Ti are preferable.

R _{4 to} R ₆ have the same meanings as R _{1 to} R ₃ , but preferably have at least either an alkoxy group or a halogen atom as a substituent.

  Although the preferable specific example of a compound represented by General formula (1) below is shown, it is not limited to these.

  Each compound mentioned as these specific examples is, for example, Collect. Czech. Chem. Commun. 44, 750-755, J. MoI. Amer. Chem. Soc. 1990, 112, 2341-2348, Inorg. Chem. 10: 889-892, 1971, U.S. Pat. No. 3,668,233, etc., JP-A 58-122979, JP-A 7-242675, JP-A 9-61605, etc. 11-29585, JP-A No. 2000-64348, JP-A No. 2000-144097 and the like, or a synthesis method based on the synthesis method.

  Since the second active layer containing the organic semiconductor material is preferably formed on the first active layer, the water contact angle of the first active layer surface-treated with the organic material is 60 degrees or more. More preferably, it is 80 degrees or more. Since the organic semiconductor material forms a thin film having a preferred orientation, the carrier mobility of the transistor element can be improved and the on / off ratio can be significantly reduced.

  The contact angle is a value of a contact angle 0.2 seconds after dropping a 2 μl droplet of the solution on a substrate in an environment of 23 ° C. and 50% RH. Measurement is performed using an automatic contact angle meter (CA-VP model manufactured by Kyowa Interface Science Co., Ltd.).

  Moreover, although there are influences, such as surface roughness, the semiconductor material solution contact angle of the surface of the 1st active layer which deposits organic-semiconductor material is 3-20 degree | times, Furthermore, 5-15 degree | times is more preferable. Moreover, the semiconductor material solution contact angle in other regions is preferably 15 to 100 degrees, and more preferably 20 to 90 degrees.

  Regarding a method for forming a monomolecular film on the first active layer, that is, a surface treatment method using a silane coupling agent, JP-A Nos. 2004-327857, 2005-32774, and 2005-158765 are disclosed. Known methods such as those disclosed in each publication of the publication can be applied. For example, a vapor phase method such as a CVD (Chemical Vapor Deposition) method, a liquid phase method such as a spin coating method or a dip coating method, and a printing method such as a screen printing method, a micromold method, a micro contact method, and an ink jet method. Etc. can be applied. Moreover, you may supply a material directly. More preferred is a solution process (liquid phase method).

  Among them, the method preferably used is preferably a method (wet method) in which the substrate is immersed in a solution of the surface treatment agent or the solution of the surface treatment agent is applied to the substrate and dried.

  In addition, before the self-assembled monomolecular film is formed, it is preferable to perform a cleaning process using oxygen plasma or the like in order to increase the reactivity.

(Wet method)
In the wet method, for example, the substrate is dipped in a 1% by weight toluene solution of a surface treatment agent for 10 minutes and then dried, or this solution is applied onto the substrate and dried. The density of the self-assembled monolayer can be adjusted by changing the immersion time and the concentration of the surface treatment agent. The solvent used is not limited as long as it selects a solvent that does not react with the surface treatment agent and dissolves it. A solvent similar to the organic solvent used when producing the organic semiconductor solution can be used.

(Plasma CVD method, atmospheric pressure plasma CVD method)
A thermal CVD method in which a reactive gas containing a surface treatment agent (also referred to as a raw material for a thin film forming material in the plasma CVD method) is supplied onto a substrate heated in a range of 50 ° C. to 500 ° C., and a thin film is formed by a thermal reaction; A general plasma CVD method performed under a reduced pressure of 0.01 Pa to 100 Pa using the above atmospheric pressure plasma apparatus, discharge gas, and reactive gas may be used. Thin film uniformity, thin film formation speed From the viewpoint of efficient production in a non-vacuum system, the atmospheric pressure plasma method is preferable.

  The thin film transistor according to the present invention having a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor and having the first and second active layers laminated is a field effect type. It can be used for a thin film transistor (TFT).

  The thin film transistor (field effect transistor) of the present invention includes, for example, a step of forming a gate electrode on an insulating substrate, a step of forming a gate insulating layer on the insulating substrate and the gate electrode, A step of forming a first active layer made of a metal oxide semiconductor, a step of forming a source / drain electrode on the first active layer, and a reverse conductivity on the source / drain electrode and the first active layer. Forming a second active layer of the mold (bottom gate structure).

  Alternatively, a step of forming a first active layer on an insulating substrate, a step of forming a source / drain electrode on the first active layer, a reverse conductivity on the first active layer and the source / drain electrode It can also be manufactured by a step of forming a second active layer of a mold, a step of forming a gate insulating layer on the second semiconductor layer, a step of forming a gate electrode on the gate insulating layer, etc. (top gate type configuration) .

  This will be described with reference to the drawings. FIG. 4 is a schematic cross-sectional view showing an example of the structure of the thin film transistor of the present invention.

  In FIG. 4A, first, a conductive material layer is formed on an insulating substrate 101 to form a gate electrode 102. Next, an insulating material is formed over the substrate and the gate electrode 102 to form the gate insulating layer 103. Next, a first active layer made of a metal oxide semiconductor is formed on the gate insulating layer 103 by the above-described method (a metal thin film is formed on the gate insulating layer and then plasma-oxidized). One active layer 104 is formed. Next, the source electrode 105a and the drain electrode 105b are formed on the first semiconductor layer 104 by a conductive material (for example, gold vapor deposition). Then, a second active layer made of a reverse conductivity type organic semiconductor is formed on the first active layer 104, the source electrode 105a, and the drain electrode 105b, and the second active layer is formed together with the first active layer 104. Layer 106 is formed.

  In FIG. 4B, after forming the gate insulating layer 103, the first active layer 104 made of a metal oxide semiconductor is formed by plasma oxidation after forming the metal thin film on the gate insulating layer. The second active layer 106 made of an organic semiconductor is further formed on the first active layer 104 by, for example, vapor deposition using a mask or a coating process such as an inkjet method or screen printing. Next, a conductive material (for example, gold) is formed on the second active layer 106 by vapor deposition or the like to form the source electrode 105a and the drain electrode 105b.

  In FIG. 4C, after the gate insulating layer 3 is formed, the first active layer 104 made of a metal oxide semiconductor is formed by plasma oxidation after forming the metal thin film on the gate insulating layer. The second active layer 106 made of an organic semiconductor is further formed on the channel oxide region by the ink jet method or screen printing, and the region where the metal oxide semiconductor thin film (first active layer 104) is formed. For example, the metal oxide semiconductor thin film surface as the first active layer 104 was formed to be exposed over a width of about 5 μm.

  Further, a conductive material (for example, gold or the like) is deposited on the surface of the first active layer 104 or the surface of the second active layer 106 made of an organic semiconductor by a mask or vapor deposition, or by a coating process such as an inkjet method or screen printing. Thus, the source electrode 105a and the drain electrode 105b are formed.

  Here, the insulating substrate 1 is, for example, an insulating substrate in which an insulating material such as a silicon oxide film is formed on glass or a plastic material. 4A and 4B, the gate electrode is formed so as to cover the gap between the source electrode and the drain electrode, but is arranged between the gap between the source electrode and the drain electrode. Even if configured, a channel is formed in the semiconductor layer under the gate electrode through the insulating film, and a field effect transistor operation can be performed.

  In FIGS. 4A and 4B, the source / drain electrodes are formed on one active layer, but the source / drain electrodes are formed on both the semiconductor layers of the first active layer and the second active layer. However, the positional relationship is not limited to FIGS. 4A and 4B. The configuration shown in FIG. 4C is preferable from the viewpoint of contact resistance because the source / drain electrodes are formed in contact with both the semiconductor layers of the first active layer and the second active layer.

  In the configuration of FIG. 4A, the second active layer is formed after the source electrode and the drain electrode are formed. The surface of the source electrode and the drain electrode is subjected to a surface treatment made of an organic material. preferable. As the surface treatment made of an organic substance, it is preferable to form a monomolecular film on the source electrode and the drain electrode by physical adsorption or chemical adsorption. For example, alkyl or aryl thiol (for example, octyl thiol, pentafluorophenyl thiol) or the like is used. .

  In FIG. 4, the first active layer made of a metal oxide semiconductor having n-type semiconductor characteristics is disposed on the side close to the gate electrode as viewed from the gate electrode. Alternatively, the second active layer may be arranged on the side close to the gate electrode.

  However, when viewed from the manufacturing process, it is more productive to form the organic semiconductor layer on the metal oxide semiconductor layer, and there is less disturbance of the interface when formed in this order, and the characteristics can be stabilized. Preferably, a transistor having better device characteristics than a transistor in which an n-type material is arranged on a p-type material can be realized.

  For example, even in the case of having a top-gate configuration, whichever is the upper side (that is, closer to the gate) is the active layer made of an n-type material, that is, a metal oxide semiconductor, and the second active layer made of a p-type material, that is, an organic semiconductor. The second active layer made of a p-type material, that is, an organic semiconductor is preferably disposed on the active layer made of an n-type material, that is, a metal oxide semiconductor. .

  The second active layer, which is preferably a p-type material layer, is preferably composed of an organic semiconductor having a thickness of about 10 to 100 nm. The first active layer, which is preferably an n-type material layer, is preferably composed of an inorganic oxide semiconductor layer having a thickness of about 10 to 100 nm.

  For example, specifically, the first active layer 104 is an n-type metal oxide semiconductor layer formed of, for example, an alloy of In, Zn, and Ga having a composition ratio of 1: 1: 1. The layer 106 is a p-type organic semiconductor layer formed of, for example, pentacene or oligothiophene.

  The inventor of the present invention has found that the device characteristics can be substantially improved by adopting such a configuration. In particular, the “off” current (off current) between the source and drain can be significantly reduced, thus improving the on / off ratio of the transistor.

  The decrease in “off” current is caused by contact between the second active layer 106 made of a suitable organic semiconductor material and the first active layer 104 made of a metal semiconductor layer, specifically pentacene, oligothiophene, etc. and In , Zn, and Ga are considered to be related to an interface with an oxide semiconductor formed of an alloy having a 1: 1: 1 composition ratio.

  In particular, the formation of the second active layer on the first active layer in the present invention has a great effect because the disturbance of the interface can be reduced.

  FIG. 5 shows a schematic equivalent circuit diagram of an example of a thin film transistor sheet 120 in which a plurality of thin film transistor elements of the present invention are arranged.

  The thin film transistor sheet 120 has a large number of thin film transistor elements 124 arranged in a matrix. 121 is a gate bus line of the gate electrode of each thin film transistor element 124, and 122 is a source bus line of the source electrode of each thin film transistor element 124. An output element 26 is connected to the drain electrode of each thin film transistor element 124. The output element 126 is, for example, a liquid crystal or an electrophoretic element, and constitutes a pixel in the display device. In the illustrated example, a liquid crystal is shown as an output element 126 by an equivalent circuit composed of a resistor and a capacitor. Reference numeral 125 denotes a storage capacitor, 127 denotes a vertical drive circuit, and 28 denotes a horizontal drive circuit.

  The present invention can be used for such a sheet in which thin film transistor elements are two-dimensionally arranged on a support.

  The thin film transistor of the present invention has a p-type channel material (second active layer made of an organic semiconductor) when the gate is negatively biased with respect to the source due to the energy levels of the organic semiconductor material layer and the metal oxide semiconductor material layer. ) Is filled with holes, and when the gate is positively biased with respect to the source, the n-type channel material (with the first active layer made of a metal oxide semiconductor) is filled with electrons. It will be obvious to those skilled in the art.

  FIG. 6 is a diagram schematically showing gate voltage-drain current characteristics of the transistor shown in FIG. Note that FIG. 6 shows that a single transistor can be used as both a p-type channel and an n-type channel device.

  Complementary circuits using transistors (based on silicon) according to the prior art are known and are known to be capable of low power consumption operation. For example, W.W. N. Carr et al. , "MOS / LSI Design and Applications" (McGraw-Hill), pages 77-78. In the complementary circuit according to the prior art, which transistor is an n-type channel and which transistor is a p-type channel is determined in advance (through selection of impurities).

  The thin film transistor according to the present invention can be used as either a p-type channel or an n-type channel device depending on the applied bias voltage. This gives the circuit designer additional freedom. Because a given transistor becomes a p-type channel device under one bias condition and an n-type channel device under another bias condition, one transistor functions as an n-type channel device and the other as a p-type channel device. Function.

(electrode)
In the present invention, the conductive material used for the electrodes such as the source electrode, the drain electrode, and the gate electrode constituting the TFT element is not particularly limited as long as it has conductivity at a practical level as an electrode. , Gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin / antimony oxide, indium / tin oxide ( ITO), fluorine-doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium Sodium - potassium alloy, magnesium, lithium, aluminum, magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, a lithium / aluminum mixture, or the like is used.

  Moreover, as a conductive material, a conductive polymer, metal fine particles, or the like can be suitably used. As the dispersion containing metal fine particles, for example, a known conductive paste may be used, but a dispersion containing metal fine particles having a particle diameter of 1 nm to 50 nm, preferably 1 nm to 10 nm is preferable. In order to form an electrode from metal fine particles, the above-described method can be used in the same manner, and the metal described above can be used as the material of the metal fine particles.

(Method for forming electrodes, etc.)
As a method for forming an electrode, a method for forming an electrode using a known photolithographic method or a lift-off method from a conductive thin film formed by using a method such as vapor deposition or sputtering using the above as a raw material, or a metal foil such as aluminum or copper There is a method in which a resist is formed and etched by thermal transfer, ink jet or the like. Alternatively, a conductive polymer solution or dispersion, a dispersion containing metal fine particles, or the like may be directly patterned by an ink jet method, or may be formed from a coating film by lithography or laser ablation. Further, a method of patterning a conductive ink or conductive paste containing a conductive polymer or metal fine particles by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing can also be used.

  As a method of forming an electrode such as a source, drain, or gate electrode, a gate, or a source bus line without patterning a metal thin film using a photosensitive resin such as etching or lift-off, there is a method by an electroless plating method. Are known.

  Regarding the method for forming an electrode by an electroless plating method, as described in Japanese Patent Application Laid-Open No. 2004-158805, a liquid containing a plating catalyst that acts on a plating agent to cause electroless plating is applied to a portion where the electrode is provided. For example, after patterning by a printing method (including inkjet printing), a plating agent is brought into contact with a portion where an electrode is provided. If it does so, electroless plating will be performed to the said part by the contact of the said catalyst and a plating agent, and an electrode pattern will be formed.

  The application of the electroless plating catalyst and the plating agent may be reversed, and the pattern formation may be performed either. However, a method of forming a plating catalyst pattern and applying the plating agent to this is preferable.

  As the printing method, for example, screen printing, lithographic printing, letterpress printing, intaglio printing, ink jet printing, or the like is used.

(Gate insulation film)
Although various insulating films can be used as the gate insulating film of the thin film transistor of the present invention, an inorganic oxide film having a high relative dielectric constant is particularly preferable. Inorganic oxides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Examples thereof include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and yttrium trioxide. Of these, silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide are preferable. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  Examples of the method for forming the film include a vacuum process, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD method, a sputtering method, an atmospheric pressure plasma method and the like, spraying Wet processes such as coating methods, spin coating methods, blade coating methods, dip coating methods, casting methods, roll coating methods, bar coating methods, die coating methods, and other wet processes such as printing and ink jet patterning methods, etc. Can be used depending on the material.

  The wet process is a method of applying and drying a liquid in which fine particles of inorganic oxide are dispersed in an arbitrary organic solvent or water using a dispersion aid such as a surfactant as required, or an oxide precursor, for example, A so-called sol-gel method in which a solution of an alkoxide body is applied and dried is used.

  Of these, the atmospheric pressure plasma method described above is preferable.

  It is also preferable that the gate insulating film (layer) is composed of an anodized film or the anodized film and an insulating film. The anodized film is preferably sealed. The anodized film is formed by anodizing a metal that can be anodized by a known method.

  Examples of the metal that can be anodized include aluminum and tantalum, and the anodizing method is not particularly limited, and a known method can be used.

  Examples of organic compound films include polyimides, polyamides, polyesters, polyacrylates, photo-radical polymerization-type, photo-cation polymerization-type photo-curing resins, copolymers containing acrylonitrile components, polyvinyl phenol, polyvinyl alcohol, novolac resins, etc. Can also be used.

  An inorganic oxide film and an organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

(substrate)
Various materials can be used as the support material constituting the substrate. For example, ceramic substrates such as glass, quartz, aluminum oxide, sapphire, silicon nitride, silicon carbide, silicon, germanium, gallium arsenide, gallium phosphide. In addition, a semiconductor substrate such as gallium nitrogen, paper, and non-woven fabric can be used. In the present invention, the support is preferably made of a resin, for example, a plastic film sheet can be used. Examples of plastic films include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include films made of triacetate (TAC), cellulose acetate propionate (CAP), and the like. By using a plastic film, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved.

  An element protective layer can be provided on the thin film transistor element of the present invention. Examples of the protective layer include the inorganic oxides and inorganic nitrides described above, and it is preferable to form the protective layer by the atmospheric pressure plasma method described above.

  The following examples will specifically describe the thin film transistor according to the present invention with reference to the schematic diagram of the thin film transistor manufacturing process of FIG.

<Example 1>
As the resin support 101, a polyethersulfone resin film (200 μm) was used, and first, a corona discharge treatment was performed thereon under the condition of 50 W / m ² / min. Thereafter, an undercoat layer was formed in order to improve adhesion as follows.

(Formation of undercoat layer)
A coating solution having the following composition was applied to a dry film thickness of 2 μm, dried at 90 ° C. for 5 minutes, and then cured for 4 seconds from a distance of 10 cm under a 60 W / cm high-pressure mercury lamp.

Dipentaerythritol hexaacrylate monomer 60g
Dipentaerythritol hexaacrylate dimer 20g
Dipentaerythritol hexaacrylate trimer or higher component 20g
Diethoxybenzophenone UV initiator 2g
Silicone surfactant 1g
75g of methyl ethyl ketone
Methyl propylene glycol 75g
Further, a silicon oxide film having a thickness of 50 nm was formed on the layer by continuous atmospheric pressure plasma treatment under the following conditions, and these layers were used as the undercoat layer 108 (FIG. 7 (1)).

(Used gas)
Inert gas: helium 98.25% by volume
Reactive gas: oxygen gas 1.5 volume%
Reactive gas: Tetraethoxysilane vapor (bubbled with helium gas) 0.25% by volume
(Discharge conditions)
Discharge output: 10 W / cm ²
(Electrode condition)
The electrode is coated with 1 mm of alumina by ceramic spraying on a stainless steel jacket roll base material having cooling means with cooling water, and then a solution obtained by diluting tetramethoxysilane with ethyl acetate is applied and dried, and then sealed by ultraviolet irradiation. This is a roll electrode having a dielectric (relative permittivity of 10) that has been subjected to hole treatment and has a smooth surface and an Rmax of 5 μm, and is grounded. On the other hand, as the application electrode, a hollow rectangular stainless steel pipe was coated with the same dielectric as described above under the same conditions.

  Next, a gate electrode is formed. An aluminum film having a thickness of 300 nm was formed on one surface by sputtering, and then etched by photolithography to form the gate electrode 102 (FIG. 7 (2)).

(Anodized film forming process)
After the gate electrode 102 is formed, the substrate is thoroughly washed, and a direct current supplied from a constant voltage power source of 30 V is used for 2 minutes in a 30% by mass ammonium phosphate aqueous solution until the thickness of the anodized film reaches 120 nm. Anodization was performed (not shown in the figure).

  Next, at a film temperature of 200 ° C., a silicon oxide film having a thickness of 30 nm is provided by the atmospheric pressure plasma method described above, and the above-described anodized aluminum layer is combined to form a gate insulating film 103 having a thickness of 150 nm (FIG. 7 (3)).

  Next, tetra-i-propoxytin and diethoxyzinc were dissolved in toluene at a molar ratio of 1: 1 to prepare a 5 mass% solution. This solution was discharged onto a gate insulating film provided with a gate electrode using an ink jet apparatus, and the solvent was cast to form a thin film having an average film thickness of 30 nm.

  Further, in the atmospheric pressure plasma method, the oxidation treatment was performed under the following conditions.

(Used gas)
Inert gas: Helium 99.5% by volume
Reactive gas: Oxygen gas 0.5% by volume
(Discharge conditions)
High frequency power supply: 13.56 MHz
Discharge output: 10 W / cm ²
Oxidation treatment was performed at a resin support (film) temperature of 200 ° C. The first active layer 104 made of a metal oxide semiconductor having a thickness of about 30 nm was converted (FIG. 7 (4)).

  Next, a source electrode 105a and a drain electrode 105b were formed by a lift-off method including steps of resist formation by photolithography, gold vapor deposition, and resist peeling (FIG. 7 (5)). Each size was 10 μm wide, 50 μm long (channel width), and 50 nm thick, and the distance (channel length) between the source electrode 105a and the drain electrode 105b was 15 μm.

  After dry cleaning by UV ozone treatment, it was immersed for 3 minutes in a 5 mass% ethanol solution of pentafluorobenzenethiol. Furthermore, hexamethyldisilazane was applied by spin coating at 3000 rpm, and a heat treatment at 90 ° C. for 2 minutes was performed.

  Next, an organic semiconductor layer was formed using OSC2-1 as the organic semiconductor material. That is, a xylene solution (0.5% by mass) of OSC2-1 was prepared and discharged onto the source / drain electrodes and the channel region by using a piezo ink jet method (FIG. 7 (6)). And dried at 50 ° C. for 3 minutes. By drying, a second active layer 106 made of an organic semiconductor having a thickness of 30 nm was formed in the channel region (FIG. 7 (7)).

  The transistor characteristics of the thin film transistor element obtained above were evaluated, and the operating characteristics of the p-channel enhancement type FET were shown in the negative gate bias region.

An increase in drain current (transfer characteristics) was observed when the drain bias was −15 V and the gate bias was swept from +10 V to −30 V. The carrier mobility estimated from the saturation region was 1.0 cm ² / Vs, the on / off ratio was 7 digits, and the threshold was −3V.

Similarly, in the region where the gate bias is positive, the operating characteristics of the n-channel enhancement type FET are also shown. An increase in drain current (transfer characteristic) was observed when the drain bias was +15 V and the gate bias was swept from -10 V to +30 V. The carrier mobility estimated from the saturation region was 6 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was +5 V.

  As described above, the thin film transistor of the present invention exhibits both n-type and p-type drive characteristics.

<Example 2>
FIG. 8 shows the process.

  In the same manner as in Example 1, after providing the first active layer 104 made of a metal oxide semiconductor thin film (FIG. 8 (1)), hexamethyldisilazane was applied by spin coating at 3000 rpm, and 90 ° C. for 2 minutes. The heat treatment was performed. Thereafter, similarly to Example 1, a second active layer 106 made of an organic semiconductor thin film was formed using the organic semiconductor OSC2-1 (FIG. 8B).

  Next, gold was deposited using a mask to form a source electrode 105a and a drain electrode 105b (FIG. 8 (3)).

A cross-sectional view of this thin film transistor is shown. The first active layer was formed in a region having a length of about 300 μm and a width (X ₁ ) of 60 μm. The second active layer was formed in a region having a length of about 300 μm and a width (X ₂ ) of 50 μm, and was arranged so as to be located in the width direction, center portion on the first active layer. Each of the source electrode 105a and the drain electrode 105b has a width of 40 μm, a length of 250 μm (channel width), and a thickness of 50 nm, and the length direction is the length of the first active layer and the second active layer. Arranged parallel to the direction. Further, the distance L (channel length) between the electrodes is set to 30 μm, and the channel portion is located at the center in the width direction of the first active layer and the second active layer.

When the characteristics of the thin film transistor were measured under exactly the same conditions as in Example 1, the driving characteristics of both n-type operation and p-type operation were shown. The carrier mobility during p-type operation was 0.8 cm ² / Vs, on / The off ratio was 7 digits and the threshold was -5V. Moreover, the carrier mobility at the time of n-type operation was 6 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was + 5V.

<Example 3>
In the same manner as in Example 1, a first active layer 104 made of a metal oxide semiconductor thin film was provided (FIG. 9 (1)). Thereafter, hexamethyldisilazane was applied by spin coating at 3000 rpm, and a heat treatment at 90 ° C. for 2 minutes was performed. Thereafter, similarly to Example 1, a second active layer 106 made of an organic semiconductor thin film was formed using the organic semiconductor OSC2-1. At this time, since the discharge amount of the organic semiconductor solution was increased by 50%, unlike Example 2, the organic semiconductor thin film region was formed to completely cover the region of the metal oxide semiconductor thin film (FIG. 9 (2)). .

  Next, gold was deposited using a mask to form a source electrode 105a and a drain electrode 105b (FIG. 9 (3)).

The first active layer was formed in a region having a length of about 300 μm and a width (X ₁ ) of 60 μm. The second active layer was formed in a region having a length of about 300 μm and a width (X ₂ ) of 70 μm, and was arranged so as to be located in the lateral direction and the central portion on the first active layer. Each of the source electrode 105a and the drain electrode 105b has a width of 40 μm, a length of 250 μm (channel width), and a thickness of 50 nm, and the length direction is the length of the first active layer and the second active layer. Arranged parallel to the direction. Further, the distance L (channel length) between the electrodes is set to 30 μm, and the channel portion is located at the center in the width direction of the first active layer and the second active layer.

When the thin film transistor was measured under exactly the same conditions as in Example 1, the driving characteristics of both n-type operation and p-type operation were shown, and carrier mobility during p-type operation was 0.8 cm ² / Vs, on / off ratio. Was 7 digits and the threshold was -5V. In addition, the carrier mobility at the time of n-type operation was 0.5 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was +8 V.

<Example 4>
FIG. 8 shows the process.

  After forming the gate insulating film 103 in the same manner as in Example 1, the formation of the first active layer made of the metal oxide semiconductor thin film of Example 1 was changed as follows.

  Indium nitrate and zinc nitrate were dissolved in ultrapure water at a molar ratio of 1: 1 to prepare a 5 mass% solution. This solution was discharged onto a gate insulating film provided with a gate electrode using an ink jet apparatus, and the solvent was cast to form a thin film having an average film thickness of 30 nm.

  Further, in the atmospheric pressure plasma method, the oxidation treatment was performed under the following conditions.

(Used gas)
Inert gas: Helium 99.5% by volume
Reactive gas: Oxygen gas 0.5% by volume
(Discharge conditions)
High frequency power supply: 13.56 MHz
Discharge output: 10 W / cm ²
Oxidation treatment was performed at a resin support (film) temperature of 200 ° C. By the oxidation treatment, the metal thin film was changed to be transparent and converted to a metal oxide semiconductor having a thickness of about 30 nm, and the first active layer 104 was formed (FIG. 8 (1)).

  Next, hexamethyldisilazane was applied by spin coating at 3000 rpm, and heat treatment was performed at 90 ° C. for 2 minutes. Thereafter, in the same manner as in Example 1, a second active layer made of an organic semiconductor was formed using the organic semiconductor OSC2-1 (FIG. 8 (2)).

  Next, gold was deposited using a mask to form a source electrode 105a and a drain electrode 105b (FIG. 8 (3)).

The first active layer was formed in a region having a length of about 300 μm and a width (X ₁ ) of 60 μm. The second active layer was formed in a region having a length of about 300 μm and a width (X ₂ ) of 50 μm, and was arranged so as to be located in the width direction, center portion on the first active layer. Each of the source electrode 105a and the drain electrode 105b has a width of 40 μm, a length of 250 μm (channel width), and a thickness of 50 nm, and the length direction is the length of the first active layer and the second active layer. Arranged parallel to the direction. Further, the distance L (channel length) between the electrodes is set to 30 μm, and the channel portion is located at the center in the width direction of the first active layer and the second active layer.

When the thin film transistor was measured under exactly the same conditions as in Example 1, the driving characteristics of both n-type operation and p-type operation were shown, and carrier mobility during p-type operation was 1.1 cm ² / Vs, on / off ratio. Was 6 digits and the threshold was -6V. Further, the carrier mobility during n-type operation was 5 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was +6 V.

<Example 5>
Example 4 shows an example in which the upper and lower sides of the semiconductor layer are interchanged. The process is shown in FIG.

  In the same manner as in Example 1, after providing the gate insulating film 103, hexamethyldisilazane was applied by spin coating at 3000 rpm, and heat treatment was performed at 90 ° C. for 2 minutes.

  Next, similarly to Example 1, a second active layer 106 made of an organic semiconductor thin film was formed using the organic semiconductor OSC2-1 (FIG. 10 (1)). A first active layer 104 made of a metal oxide semiconductor thin film is formed thereon. That is, indium nitrate and zinc nitrate were dissolved in ultrapure water at a molar ratio of 1: 1 to prepare a 5% by mass solution. This solution was discharged onto a second active layer made of an organic semiconductor using an ink jet apparatus, and water as a solvent was cast to form a precursor thin film having an average film thickness of 30 nm.

  Further, in the atmospheric pressure plasma method, the oxidation treatment was performed under the following conditions.

(Used gas)
Inert gas: Helium 99.5% by volume
Reactive gas: Oxygen gas 0.5% by volume
(Discharge conditions)
High frequency power supply: 13.56 MHz
Discharge output: 10 W / cm ²
Oxidation treatment was performed at a resin support (film) temperature of 200 ° C. The metal thin film turned transparent by the oxidation treatment, and was converted to an oxide semiconductor thin film (first active layer 104) made of a metal oxide having a thickness of about 30 nm (FIG. 10 (2)).

  Next, gold was deposited using a mask to form a source electrode 105a and a drain electrode 105b (FIG. 10 (3)).

The second active layer was formed in a region having a length of about 300 μm and a width (X ₂ ) of 60 μm. The first active layer was formed in a region having a length of about 300 μm and a width (X ₁ ) of 50 μm, and was arranged so as to be positioned in the width direction and center portion on the second active layer. Each of the source electrode 105a and the drain electrode 105b has a width of 40 μm, a length of 250 μm (channel width), and a thickness of 50 nm, and the length direction is the length of the first active layer and the second active layer. Arranged parallel to the direction. Further, the distance L (channel length) between the electrodes is set to 30 μm, and the channel portion is located at the center in the width direction of the first active layer and the second active layer.

When the thin film transistor was measured under exactly the same conditions as in Example 1, it showed both n-type and p-type drive characteristics, and carrier mobility during p-type operation was 0.7 cm ² / Vs, on / off ratio. Was 6 digits and the threshold was -3V. The carrier mobility during n-type operation was 0.2 cm ² / Vs, the on / off ratio was 5 digits, and the threshold was +15 V.

<Example 6>
In Example 1, a thin film transistor was fabricated without performing treatment with pentafluorobenzenethiol and hexamethyldisilazane, which are surface treatments on the first active layer.

When the thin film transistor was measured under exactly the same conditions as in Example 1, the driving characteristics of both n-type operation and p-type operation were shown, and carrier mobility during p-type operation was 0.3 cm ² / Vs, on / off ratio Was 6 digits and the threshold was -7V. Further, the carrier mobility during n-type operation was 5 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was +6 V.

<Example 7>
In Example 1, the surface treatment of the first active layer with pentafluorobenzenethiol was not performed, but only the treatment with hexamethyldisilazane was performed. The hexamethylsilazane treatment was applied by spin coating at 3000 rpm and heat treatment at 90 ° C. for 2 minutes as in Example 1.

When the thin film transistor was measured under exactly the same conditions as in Example 1, the driving characteristics of both n-type operation and p-type operation were shown, and carrier mobility during p-type operation was 0.8 cm ² / Vs, on / off ratio. Was 7 digits and the threshold was -4V. Further, the carrier mobility at the time of n-type operation was 6 cm ² / Vs, the on / off ratio was 6 digits, and the threshold was + 6V.

<Comparative example>
In Example 2, the n-type semiconductor was changed from a metal oxide semiconductor to copper fluoride phthalocyanine (F ₁₆ CuPc) used in Japanese Patent Application Laid-Open No. 2004-235624. Aldrich copper fluoride phthalocyanine was purified by sublimation to prepare an n-type semiconductor material.

  After providing the gate insulating film 103, copper fluoride phthalocyanine was heated and evaporated thereon to form an n-type semiconductor layer having a thickness of 30 nm.

  Thereafter, as in Example 2 (process is shown in FIG. 8), an organic semiconductor layer was formed using the organic semiconductor OSC2-1. At this time, the organic semiconductor region did not exceed the region of the oxide semiconductor thin film, and the oxide semiconductor thin film as the first active layer was exposed over a width of about 5 μm (FIG. 8B).

  Next, gold was deposited using a mask to form a source electrode 105a and a drain electrode 105b (FIG. 8 (3)). Each size was 10 μm wide, 50 μm long (channel width), and 50 nm thick, and the distance (channel length) between the source electrode 105a and the drain electrode 105b was 15 μm.

The characteristics of the thin film transistor were measured under exactly the same conditions as in Example 1. As a result, the driving characteristics of both the n-type operation and the p-type operation were shown, and the carrier mobility during the p-type operation was 0.00003 cm ² / Vs, on / The off ratio was 2 digits and the threshold was -35V. The carrier mobility during n-type operation was 0.0001 cm ² / Vs, the on / off ratio was two digits, and the threshold was +45 V.

Claims (11)

A thin film transistor comprising a first active layer made of a metal oxide semiconductor and a second active layer made of an organic semiconductor, wherein the first and second active layers are stacked. 2. The thin film transistor according to claim 1, wherein a second active layer is formed on the first active layer. 3. The thin film transistor according to claim 1, wherein the surface of the first active layer is subjected to a surface treatment with an organic substance. The thin film transistor according to any one of claims 1 to 3, wherein at least the second active layer is formed by casting from a solution. The thin film transistor according to any one of claims 1 to 4, wherein the first active layer is formed by a process including a cast from a solution. The thin film transistor according to any one of claims 1 to 5, wherein the thin film transistor exhibits driving characteristics of both an n-type channel operation and a p-type channel operation. The thin film transistor according to any one of claims 1 to 6, wherein the second active layer is a p-type semiconductor. The thin film transistor according to any one of claims 1 to 7, wherein the first active layer made of a metal oxide semiconductor contains any one of In, Zn, and Sn. The thin film transistor according to any one of claims 1 to 8, wherein the first active layer made of a metal oxide semiconductor contains Ga and Al. The thin film transistor according to any one of claims 1 to 9, wherein the second active layer made of an organic semiconductor contains a compound represented by the following general formula (OSC1).

(Wherein R _{1 to} R ₆ represent a hydrogen atom or a substituent, Z ₁ or Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocyclic ring, n1 or n2 represents an integer of 0 to 3.) The thin film transistor according to any one of claims 1 to 10, wherein the first active layer is in contact with a source and a drain by a top contact type configuration.