CN103646855B - The manufacture method of graphene device - Google Patents

Abstract

The invention provides a method for making a graphene device, the method for making a graphene device at least includes: providing a first substrate; forming a PVA layer on the first substrate; forming a PMMA layer on the PVA layer ; Form a graphene device on the PMMA layer; Put the first substrate, the PVA layer, the PMMA layer and the graphene device into deionized water to dissolve the PVA layer, so that the The PMMA layer and the graphene device are separated from the first substrate; the PMMA layer and the graphene device are transferred onto a second substrate. The present invention adopts PMMA to make supporting layer, utilizes PVA simultaneously as sacrificial layer, then, by removing PVA again, the graphene device that is formed on the PMMA layer is separated from first substrate together with described PMMA layer, and then with the second substrate (in this embodiment, a polyimide substrate) is bonded, so as to realize the formation of graphene devices on the second substrate. This can expand the range of applications of graphene devices.

Description

Fabrication method of graphene device

technical field

The invention relates to a semiconductor technology, in particular to a method for manufacturing a graphene device.

Background technique

Graphene is a two-dimensional crystal composed of carbon atoms that is stripped from graphite materials. It is only the thickness of one layer of carbon atoms. It is the thinnest and hardest material so far. Its unique structure makes it display a series of peculiar physical properties. Features, such as high electrical conductivity, thermal conductivity, light transmittance, high mobility and mechanical strength, etc. Graphene has a series of important photoelectric properties such as transparency, softness, continuously adjustable energy band structure, and high electron mobility. Graphene-based electronic devices have important application prospects in the field of next-generation nanoelectronic devices, such as light-emitting diodes, Solar cells and nanogenerators, etc. These superior physical properties indicate that graphene can be used as an excellent semiconductor material combined with different substrates and widely used in the fields of electronics, sensors and energy.

With the continuous advancement of research and technology, the function of graphene-based devices will be further improved, and will become an important member of future nano-devices. However, most of the current research on the preparation process of graphene field effect transistors uses semiconductor silicon as the substrate due to the integration of low-temperature processing technology and high-K dielectric preparation technology. However, on any substrate such as an organic or inorganic substrate, rigidity and Large-scale integration of nanodevices with high performance on flexible substrates remains challenging.

Contents of the invention

In view of the above-mentioned shortcoming of prior art, the object of the present invention is to provide a kind of manufacture method of graphene device, be used to solve the graphene field effect transistor preparation process in the prior art and mostly adopt semiconductor silicon as substrate, make graphite However, the application of graphene devices is limited.

In order to achieve the above-mentioned purpose and other related purposes, the invention provides a kind of preparation method of graphene device, the preparation method of described graphene device comprises at least:

providing a first substrate;

forming a PVA layer on the first substrate;

Forming a PMMA layer on the PVA layer;

Forming a graphene device on the PMMA layer;

The first substrate, the PVA layer, the PMMA layer and the graphene device are put into deionized water to dissolve the PVA layer, so that the PMMA layer and the graphene device are compatible with the first substrate detachment;

Transferring the PMMA layer and the graphene device onto a second substrate.

Preferably, the step of forming a graphene device on the PMMA layer comprises:

Forming a graphene layer on the PMMA layer;

forming a first metal layer on the graphene layer by a deposition process;

Forming the first metal layer into the source and drain of the graphene device using a photolithography process and a wet etching process;

forming a gate dielectric layer on the graphene layer, the source and the drain;

forming a second metal layer on the gate dielectric layer by a deposition process;

Forming the second metal layer into a metal top gate electrode by using a photolithography process and a wet etching process, and the metal top gate electrode is located on the gate dielectric layer between the source electrode and the drain electrode;

The gate dielectric layer above the source and the drain is removed by using a photolithography process and a wet etching process, so as to expose the source and the drain.

Preferably, the method for forming the graphene layer is a mechanical exfoliation method.

Preferably, the first metal layer is Au with a thickness of 50nm-100nm, and the formation process is electron beam evaporation.

Preferably, in the step of forming the source and drain electrodes of the graphene device from the first metal layer using a photolithography process and a wet etching process, the mixed solution of K2 and I2 is used to etch the first metal layer.

Preferably, the gate dielectric layer is a high-K dielectric material with a thickness of 10 nm to 30 nm.

Preferably, the gate dielectric layer is Al2O3, and the formation process is atomic layer deposition, and the reaction temperature is set to 150° C. during the atomic layer deposition.

Preferably, the second metal layer is copper, and the thickness is formed by electron beam evaporation.

Preferably, in the step of forming the second metal layer into a metal top gate electrode using a photolithography process and a wet etching process, the second metal layer is etched with the ferric chloride hexahydrate solution.

Preferably, the first substrate is a silicon substrate.

Preferably, the second substrate is an organic substrate, a sapphire substrate, a glass substrate, a GaN substrate, an AlN substrate, a plastic substrate or a metal substrate.

Preferably, the second substrate is a polyimide substrate.

Preferably, after transferring the PMMA layer and the graphene device to the second substrate, it also includes baking the PMMA layer, the graphene device, and the second substrate at 70° C. for 10 min. A step of.

Preferably, the thickness of the PVA layer is 80nm-120nm.

Preferably, the thickness of the PMMA layer is 180nm-250nm.

As mentioned above, the manufacturing method of the graphene device of the present invention has the following beneficial effects:

In the present invention, PMMA is used as a supporting layer, the graphene device is formed on the PMMA layer, and PVA is used as a sacrificial layer to bond the PMMA layer on the first substrate (silicon substrate in this embodiment), and then , and then by removing the PVA, the graphene device formed on the PMMA layer is separated from the first substrate together with the PMMA layer, and then the PMMA layer carrying the graphene device and the second substrate (this implementation In this case, a polyimide substrate) is bonded to form a graphene device on a second substrate. This can break through the limitation that graphene devices can only be made on silicon substrates at present, and expand the application range of graphene devices.

In addition, in the process of forming the graphene device, a low-temperature process is used to form the dielectric layer, and photolithography and wet etching are used to form various components in the graphene device, avoiding high-temperature processes, plasma processes, acetone and other processes, Therefore, the impact on the PVA layer and the PMMA layer in the process is avoided, thereby ensuring that the graphene device can be completely formed and transferred to the second substrate completely.

Description of drawings

1 to 10 are schematic diagrams showing a method for fabricating a graphene device of the present invention.

Component designation description

detailed description

The present invention will provide a kind of manufacturing process of transferable graphene device, at least comprise: form PVA layer on described first substrate; Form PMMA layer on described PVA layer, prepare graphene on described PMMA layer device, then dissolve the PVA layer, transfer the graphene device and the PMMA layer together to the polyimide substrate, realize the formation of the graphene device on the flexible polymer substrate, and the device switch ratio on the flexible polymer substrate It can reach 10 ^-6 , and the device can still work normally after many times of bending.

In addition, the present invention is also suitable for transferring the prepared graphene device to other substrates, so as to realize the improvement of the function of the graphene electronic device and its wider application.

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figure 1 through Figure 10. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

Specifically, as shown in Figure 1, the manufacturing process of the graphene device provided in this embodiment at least includes:

First, as shown in FIG. 1 , step S10 is performed: providing a first substrate 100;

In this embodiment, the first substrate 100 is a silicon substrate.

Next, step S20 is performed: forming a PVA (PolyvinylAlcohol, polyvinyl alcohol) layer 210 on the first substrate;

PVA is a water-soluble high molecular polymer, which is made of vinyl acetate through polymerization and alcoholysis. It has unique properties, such as better adhesion, flexibility, smoothness, solvent resistance and other excellent properties.

In this embodiment, PVA is used as a sacrificial layer to bond the first substrate 100 with the devices formed in subsequent processes, and then be dissolved, so that the formed devices can be transferred.

However, PVA will react with Ar, H ₂ and O ₂ plasma at high temperature, so in the subsequent process, it is necessary to avoid high process temperature, and avoid Ar/H ₂ annealing, O ₂ plasma deal with.

Specifically, in this embodiment, the PVA layer 210 is formed on the first substrate 100 by spin coating, and the thickness of the PVA layer 210 is about 100 nm, specifically 80 nm˜120 nm.

Next, step S30 is performed: forming a PMMA (Polymethylmethacrylate, polymethyl methacrylate) layer 220 on the PVA layer 210;

PMMA has the advantages of light weight, high mechanical strength, easy molding, easy to dissolve in organic solvents, etc., and can form a good film and good dielectric properties, and can be used as the dielectric layer of organic field effect tubes. Therefore, in this embodiment, a PMMA layer is used as a supporting layer, and graphene devices are formed on the PMMA layer 220 in subsequent processes.

However, PMMA will react with Ar, H ₂ and O ₂ plasma at high temperature, so in the subsequent process, it is necessary to avoid high process temperature, and avoid Ar/H ₂ annealing, O ₂ plasma processing, and avoid the electron beam exposure process.

Specifically, in this embodiment, the PMMA layer 220 is formed on the PVA layer 210 by spin coating, and the thickness of the PMMA layer 220 is about 200 nm, specifically 180 nm˜220 nm.

Next, with reference to FIG. 3 to FIG. 8, step S40 is performed: forming a graphene device on the PMMA layer 220;

The graphene device may be a zero-bandgap, top-gate graphene field effect transistor, a double-layer graphene transistor, a bipolar superconducting graphene transistor, or a graphene nanoribbon field effect transistor.

Wherein, in this embodiment, the graphene device is a top-gate graphene field effect transistor, that is, the process of forming the graphene device in this step includes:

As shown in Figure 3, form graphene layer 300 on described PMMA layer 220;

In this embodiment, the graphene layer 300 is formed by a mechanical exfoliation method. So far, mechanical exfoliation is the easiest way to form graphene and requires the least laboratory conditions. Moreover, the temperature of the mechanical peeling method is relatively low, and the influence on the PVA layer 210 and the PMMA layer 220 is relatively small.

In other implementation manners, the process for forming the graphene layer 300 may also be SiC epitaxial growth method, chemical vapor deposition method or other methods.

Then, as shown in FIG. 4 , a deposition process is used to form a first metal layer 400 on the graphene layer 300;

In this embodiment, the first metal layer 400 is Au, and the deposition process is electron beam evaporation.

Among them, electron beam evaporation is a clean metal thin film deposition process. Generally, the electrons emitted by the hot wire are focused, deflected and accelerated to form an electron beam with an energy of about 10 keV, and the electron beam bombards and vaporizes a metal target placed in a container with a cooling water jacket. The evaporated metal atoms will be deposited on the substrate (such as a silicon wafer) placed near the metal target, so that a certain thickness of metal coating is obtained on the substrate.

During this process, the temperature around the substrate will not be too high, which will have little effect on the PVA layer 210 and the PMMA layer 220 .

Then, as shown in FIG. 5 , the source electrode 410 and the drain electrode 420 of the graphene device are formed from the first metal layer 400 by a photolithography process and a wet etching process;

Specifically, this step includes: forming a photoresist layer (not shown) on the first metal layer 400; then exposing and developing the photoresist layer on the first metal layer 400 to Form the pattern of the source region and the drain region of the graphene device on the photoresist layer; take the photoresist layer with the source region and the drain region pattern again as a mask, utilize K ₂ and I ₂ The mixed solution performs wet etching on the first metal layer, so that the first metal layer 400 forms the source electrode 410 and the drain electrode 420 of the graphene device. In addition, this step also includes removing the remaining photoresist on the first metal layer 400 .

In this step, the process of forming the source electrode 410 and the drain electrode 420 from the first metal layer 400 is a photolithography process and wet etching. In the photolithography process, there is no acetone in the photoresist and developer. Or other organic solvents that can dissolve PVA and PMMA layers, adopt K in the process of etching the first metal layer and I _The mixed solution of I _carries out wet etching, avoiding the plasma dry etching of general etching metal etch, thereby avoiding the influence of electron beam exposure process and plasma on PVA and PMMA layers.

Then, as shown in FIG. 6, a gate dielectric layer 500 is formed on the graphene layer 300, the source electrode 410 and the drain electrode 420;

The gate dielectric layer 500 is a high-k dielectric layer. The material can be Al ₂ O ₃ , HfO ₂ and so on. In this embodiment, the gate dielectric layer 500 is made of Al ₂ O ₃ , and is formed by atomic layer deposition. The atomic layer deposition (ALD) is a method that can deposit a substance in the form of a single atomic layer The method of coating the surface of the substrate layer by layer. In ALD, the chemical reaction of a new atomic film is directly linked to the previous layer in such a way that only one layer of atoms is deposited per reaction. Compared with the traditional deposition process, the ALD of single atomic layer deposition has obvious advantages in the uniformity of the film layer, step coverage and thickness control.

In addition, in this embodiment, when performing the atomic layer deposition, the reaction temperature is 150°C. Such reaction temperature will not affect PVA and PMMA.

Then, as shown in FIG. 7 , a second metal layer is formed on the gate dielectric layer 500 by a deposition process, and a metal top gate electrode 600 is formed on the second metal layer by a photolithography process and a wet etching process.

The second metal layer is copper, and the deposition process for forming the second metal layer is electron beam evaporation. Similar to the step of forming the first metal layer, in the formation of the second metal layer, the temperature around the substrate is not too high, which has little influence on the PVA layer 210 and the PMMA layer 220 .

Wherein, the process of forming the metal top gate electrode 600 on the second metal layer by using photolithography process and wet etching process includes: forming a photoresist on the second metal layer, and then forming the second metal layer The photoresist on the layer is exposed and developed to form the pattern of the metal top gate electrode, and the pattern of the metal top gate electrode is located at the upper part between the source electrode 410 and the drain electrode 420 . Then, using the photoresist with the pattern of the metal top gate electrode as a mask, the second metal layer is etched to form the metal top gate electrode 600, and the metal top gate electrode 600 is located on the on the gate dielectric layer 500 between the source electrode 410 and the drain electrode 420 . The process of etching the second metal layer is wet etching using the ferric chloride hexahydrate solution.

Similar to the step of forming the source electrode 410 and the drain electrode 420 , the process of forming the metal top gate electrode 600 in this step can avoid the influence on the PVA and PMMA layers.

Then, as shown in FIG. 8 , the gate dielectric layer 500 above the source electrode 410 and the drain electrode 420 is removed by using a photolithography process and a wet etching process, so as to expose the source electrode 410 and the The drain electrode 420, so far, the graphene device in this embodiment is formed.

Next, step S50 is performed: as shown in Figure 9, the first substrate, the PVA layer, the PMMA layer and the graphene device are put into deionized water 10 to dissolve the PVA layer , so that the PMMA layer and the graphene device are separated from the first substrate;

Wherein, the PVA layer is dissolved in deionized water 10, and the PMMA layer carries the graphene device floating on the water surface.

Next, step S60 is performed: as shown in FIG. 10 , transferring the PMMA layer and the graphene device onto a second substrate 101 .

In this embodiment, the second substrate 101 is a polyimide substrate. Polyimide is a polymer material with excellent comprehensive performance and process characteristics. It has hardness comparable to aluminum alloys, good strength, flexibility, and chemical and radiation stability. In this step, the PMMA layer and the graphene device are transferred to a polyimide substrate, so that the electronic product with the graphene device can have properties such as lightness, thinness and rollability.

In addition, in this step, after transferring the PMMA layer and the graphene device on the second substrate 101 (polyimide substrate), it also includes transferring the PMMA layer, the graphene device, The step of baking the second substrate 101 at 70° C. for 10 minutes is to enhance the adhesion between the second substrate 101 and PMMA.

In other embodiments, the second substrate 101 is an organic substrate, a sapphire substrate, a glass substrate, a GaN substrate, an AlN substrate, a plastic substrate or a metal substrate. The PMMA layer and the graphene device are transferred to different substrates, and the graphene device will have different applications. In this way, the graphene device is transferred from the first substrate 100 (silicon substrate in this embodiment) to the second substrate 101 through the above method, so that the application field of the graphene device is greatly expanded.

In summary, the present invention adopts PMMA to make supporting layer, described graphene device is formed on PMMA layer, utilizes PVA simultaneously as sacrificial layer, described PMMA layer is bonded on the first substrate (in this embodiment, silicon lining bottom), and then by removing the PVA, the graphene device formed on the PMMA layer together with the PMMA layer is separated from the first substrate, and then the PMMA layer carrying the graphene device is combined with the second The substrate (polyimide substrate in this embodiment) is bonded, so as to form the graphene device on the second substrate. This can break through the limitation that graphene devices can only be made on silicon substrates at present, and expand the application range of graphene devices.

In addition, in the process of forming the graphene device, a low-temperature process is used to form the dielectric layer, and photolithography and wet etching are used to form various components in the graphene device, avoiding high-temperature processes, plasma processes, acetone and other processes, Therefore, the impact on the PVA layer and the PMMA layer in the process is avoided, thereby ensuring that the graphene device can be completely formed and transferred to the second substrate completely.

Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (13)

1. the manufacture method of a graphene device, it is characterised in that the manufacture method of described graphene device at least includes:

First substrate is provided；

Described first substrate is formed PVA layer；

Described PVA layer is formed PMMA layer；

Described PMMA layer is formed graphene device；

Described first substrate, described PVA layer, described PMMA layer and described graphene device are put in deionized water, to dissolve described PVA layer so that described PMMA layer and described graphene device depart from described first substrate；

Shifting on the second substrate by described PMMA layer and described graphene device, described second substrate is RF magnetron sputtering, Sapphire Substrate, glass substrate, GaN substrate, AlN substrate, plastic or metal substrate；

Wherein, the step forming graphene device on described PMMA layer includes:

Described PMMA layer is formed graphene layer；

Utilizing electron beam evaporation process to form the first metal layer on described graphene layer, described electron beam evaporation process is placed in the container of cooling jacket to carry out；

Utilize photoetching process and wet-etching technology that described the first metal layer is formed source electrode and the drain electrode of described graphene device；

Described graphene layer, described source electrode and described drain electrode are formed gate dielectric layer；

Utilizing electron beam evaporation process to form the second metal level on described gate dielectric layer, described electron beam evaporation process is placed in the container of cooling jacket to carry out；

Utilize photoetching process and wet-etching technology that described second metal level is formed metal roof gate electrode, on described metal roof gate electrode gate dielectric layer between described source electrode and described drain electrode；

Photoetching process and wet-etching technology is utilized to remove the described gate dielectric layer above described source electrode and described drain electrode, to expose described source electrode and described drain electrode.

2. the manufacture method of graphene device according to claim 1, it is characterised in that: the method for described formation graphene layer is mechanical stripping method.

3. the manufacture method of graphene device according to claim 1, it is characterised in that: described the first metal layer is Au, and thickness is 50nm～100nm, and formation process is electron beam evaporation.

4. the manufacture method of graphene device according to claim 3, it is characterised in that: in the step of the described source electrode utilizing photoetching process and wet-etching technology that described the first metal layer is formed described graphene device and drain electrode, utilize K₂And I₂Mixed solution etch described the first metal layer.

5. the manufacture method of graphene device according to claim 1, it is characterised in that: described gate dielectric layer is high K dielectric material, and thickness is 10nm～30nm.

6. the manufacture method of graphene device according to claim 1, it is characterised in that: described gate dielectric layer is Al₂O₃, formation process is ald, and when carrying out described ald, arranging reaction temperature is 150 DEG C.

7. the manufacture method of graphene device according to claim 1, it is characterised in that: described second metal level is copper, and thickness is formation process is electron beam evaporation.

8. the manufacture method of graphene device according to claim 7, it is characterized in that: described utilize photoetching process and wet-etching technology by described second metal level formed metal roof gate electrode step in, utilize the second metal level described in ferric chloride hexahydrate solution etches.

9. the manufacture method of graphene device according to claim 1, it is characterised in that: described first substrate is silicon substrate.

10. the manufacture method of graphene device according to claim 1, it is characterised in that: described second substrate is polyimide substrate.

11. the manufacture method of graphene device according to claim 1, it is characterized in that: after described PMMA layer and described graphene device are shifted on the second substrate, also include carrying out the step that described PMMA layer, described graphene device, described second substrate are toasted at 70 DEG C 10min.

12. the manufacture method of graphene device according to claim 1, it is characterised in that: the thickness of described PVA layer is 80nm～120nm.

13. the manufacture method of graphene device according to claim 1, it is characterised in that: the thickness of described PMMA layer is 180nm～250nm.