JPS59188913A - Photo cvd device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a charged phase method (Photo Chemical
VaporDiposi Lion Photo below
o CVD) or photoplasma vapor phase method (I'ho
Lo Plasma CJ + commercial Vapo
The present invention relates to a photoCvD device (photochemical vapor phase application device) that can be mass-produced using rD\'position (hereinafter referred to as PPCV D).

Conventionally, in the fumate CVD method, a substrate having a surface to be formed is heated from below the substrate, and the surface to be formed, which is the upper surface of the substrate, is irradiated with light from vertically above the surface. A known method involves photoexciting a reactive gas by irradiating it with light to cause a photochemical reaction.

This conventional method had a major industrial drawback in that it was not possible to provide a surface to be formed with a size equal to or larger than the area of the irradiated light.

Furthermore, when trying to form silicon using silane, for example, some of the photo-excited silicon adheres to the light irradiation window and absorbs the irradiation light. It had the disadvantage of weakening its strength.

For this reason, although the CVD method has the advantage of not damaging the substrate surface, it has been completely impossible to apply it to mass production.

The present invention eliminates these drawbacks and proposes a CVD apparatus that can be industrially mass-produced for the first time.

In the present invention, the reactive gas causes a photochemical reaction when irradiated with light. However, the reaction products are limited to materials that do not absorb the irradiated light.

Therefore, in the present invention, in a semiconductor whose main component is silicon, 10. Infrared light having a light energy smaller than the optical gap of - is optically excited using a carbon dioxide gas laser or a far-infrared light source. In addition, for insulators such as silicon oxide, silicon nitride, and 1i carbide, ultraviolet light (2537λ, 185071 > 1
I'm in J8.

Ultraviolet light is also used in light-transmitting conductive films such as tin oxide (also referred to as indium tin oxide (CITO)).

The features of the present invention will be described below in comparison with conventional devices according to the drawings.

FIG. 1 shows an outline of a conventionally known photo-CVD apparatus.

In the drawing, a substrate (1) is placed inside the reaction vessel (2), and a heater (53) heats the reaction vessel (2) from the bottom by 200 to 400'.
It is heated to C. Further, ultraviolet light (253 nm) is irradiated (51) by a low-pressure mercury lamp (9) in a vertical direction onto the surface of the substrate (1) through the quartz plate. To reduce the adhesion of reaction products to the underside of the quartz plate, use oil (54).
is painted on. The reactive gas is a doping system (20
) from the silane (26) flows from the flowmeter (29) into the valve (2).
8) and is supplied parallel to the substrate surface (50). Hydrogen or helium as a carrier gas is supplied from (27), a photochemical reaction takes place, and a semiconductor substrate 1rA is formed on the substrate (1). Unnecessary reaction products and carrier gas are exhausted to the outside by a vacuum pump (18) through a pressure regulating valve (13).

In such conventional equipment, when forming a soric film using silane, the silane is flowed from the direction (50), and ultraviolet light is irradiated perpendicularly to the substrate, causing a surface reaction on the substrate to cause the solicon film to form. It is formed.

However, if another board is placed at (1), then (]2)
As a result, the surface of (1) was irradiated with ultraviolet light, resulting in a shadow. For this reason, photochemical reactions cannot occur on the north side of the lower substrate (1).

That is, with the conventional method, it is not possible to form a large amount on the substrate. In conventional methods, the photochemical reaction is based on the fact that the photochemical reaction on the substrate surface is rate-limiting, rather than the photochemical reaction in the reactive gas in flight. For this reason, configurations other than those shown in FIG. 1 could not be adopted.

However, in this method, since the light source is placed in the atmosphere, the quartz plate (48) is exposed to fhi (5
To prevent this, a large area cannot be used.

For this reason, only one 3-inch wafer is required as a substrate, and even theoretically it is impossible to insert five 5-inch wafers at the same time.

On the other hand, in the present invention, as a result of thorough examination of this Crucian 1-CvD method, the photochemical reaction is also performed on the reactive gas in flight, and the formation of a film on the film surface is performed using thermal energy rather than irradiation light. We have discovered that this is possible by using

That is, in the case of a silicon film, at temperatures above 250'C, for example from 300 to 350'C, ultraviolet light must be applied to the surface on which it is formed. I have found that there is no need to make it 1 go.

In addition, even at such temperatures, the film growth rate is only 0.1 to 0.3"A/sec (6λ/min to 18X/min) in the FO1-CVD method without using the mercury excitation method. I couldn't get it.

Therefore, in the apparatus of the present invention, in addition to light energy, electricity and energy are simultaneously supplied to promote the activation of the reactive gas, thereby increasing the growth rate of the reactive gas by about 10 times or more. Its feature is that it can handle up to 20 people/second.

Conventionally, in plasma CVD, the substrate surface was sputtered (t!r(g)) using plasma energy.
The VD method had been devised.

However, as a result of careful consideration of the plasma generation mechanism, the inventor discovered that the reactive gas gains strong kinetic energy at the beginning of the discharge (glow discharge), which spatters the surface on which it is formed, causing the discharge to stop once. It was found that once activated, the reactive gas does not have much kinetic energy.

Therefore, in order to make it easier to start the discharge and to prevent instability where the discharge is about to stop even after it has started, light irradiation is first applied so that a part of the reactive gas is excited. , and furthermore, by adding electrical energy to the reactive gas at the same time as light energy, it is easy to start the discharge, and it is also easy to sustain the discharge.

Below, according to the drawings, we will describe the photo-CVD apparatus of our first son.

Figure 2 shows the reaction system or CVD (PPCVD or Photo).
o CVD) method, and an outline of the apparatus for carrying out the method of the present invention is shown.

Example 1 Figure 2 shows the reaction system <1o>, )--Ping system (20),
It has a stacked yarn (30) of the present invention.

The reaction system (10) has an inner volume of the reaction container (2) (width 90 cm
A substrate (X height C 10 cm y depth 120 cm) serving as a surface to be formed is held in a quartz holder (19).

The boulder is 65cm x 65cm, but has a length of 20cm in the flow direction (50) of the reactive gas.
20 substrates (cm x 60 cm) (total surface area to be formed: 24,000 cmL) are inserted at the same time.

Further, the surface of the substrate (1) on which the formation is to be formed is arranged in a forest at regular intervals (2 to 10 cm, e.g. 5 cm) in the vertical direction along the flow of the reactive gas introduced from above and discharged downward. ing.

Furthermore, in the device of the present invention, a halogen heater (7
), the pressure in the space where the photochemical reaction lamp is located is adjusted by opening and closing the valve (49) so that it is equal to the pressure in the reaction vessel (2).
It is held at 1OLorr.

Therefore, the quartz substrate (48) is not damaged, and a large area (80 cm x 80 cm) can be made. Therefore, the reaction space should be 65cm x 65cm x 20-20cm in height.
It became possible to create a large space of -6O.

The substrate is heated by a halogen heater (7), e.g.
Heated to 00'C. In addition, 185 nm, 253
A photochemical reaction lamp (9) that emits light at a wavelength of 14 nm or 14 nm is provided at the same time as the upper light source and the lower light source.

As a result, a flow of reactive gas (50), an irradiation light (51)
) are arranged parallel or approximately parallel to the substrate surface, and the irradiation light irradiates the entire reaction space (44). The reactive gas flows from the inlet (11) through the quartz nozzle (3) to the reaction space (44), and through the quartz outlet (8) to the exhaust system (12).

The exhaust system discharges waste materials from a pressure regulating valve (13), a stosp valve (14), a mechanical booster pump (17), and a rotary pump (18) to the outside a1≦.
I feel sick.

The substrate is first placed in the preliminary chamber (16) using a quartz holder, and after being evacuated using the gate valve (23).
45) was opened and moved to the reaction section (44). The reactive gas is silane (2G) in the doping system (2o),
P-type reactive gas such as diborane (B,H,), or N-type reactive gas (24) such as phosphin (PH,),
A gas such as ammonia or methane (25) for adding nitrogen or carbon to silicon, and hydrogen or helium (27) as a carrier gas are measured by flowmeters (25) and hydrogen or helium (27) as carrier gas.
It is added through a valve (29) and controlled by a fan (28).

In the photoCVD apparatus of the present invention, the silane used as a reactive gas is further purified.

Specifically, regarding the silane system (3o), 1=J of ring silane in which hydrogen fluoride is mixed with silane is placed in (31) of the first container.

In Fig. 2, the second
to the container (40).

The production of ring silane '4'lj was carried out in the following manner.

First, in the Verso process, close the valve of the ring silane (31), and then connect the exhaust system and the second container to the Norso (32).
, (34), (46), (15) and open the valve (
]3).

(25), (33) and (14) are closed and the Tahoe pump (19) is closed.

A rotary pump (18) is used to evacuate to 10 torr U, preferably 10 Lorr. Furthermore, the second container (40) is heated to 150 to 250'C with a heater (39).
Heat to a temperature and perform a deaeration purge.

After the cooling, the second container (40) is cooled by the knob (13), (+ 4 )) (15)) (25)
) (33) Let (34) be closed.

Further, the controller (47) controls the valve (3G) from (35) to introduce liquefied nitrogen into the playing card (38) through the two-dorno lambda valve (37).

Vaporized unnecessary nitrogen is discharged from (42). This (4
It is effective as an energy saving measure to liquefy 2) again and reduce it to (35).

The second container (40) is thus brought to approximately -150°C.

Thereafter, the valves (32) and (46) and the cock of the first container were opened to transfer the ring silane to the second container to produce liquefied silane.

Then, the silicon oxide contained in the silicon oxide becomes silicon fluoride and water, and these and hydrogen fluoride become solid in the second container and adhere to the wall surface.

After preparing the desired amount of liquefied raw silane in this container, close the valve (4G) (32> and the second container), and use the controller (47) to adjust the second container to 65 to -110'C1. For example, it is maintained at -90'C.After the pressure inside the second container is detected at (41), it is passed through the valve (33) to the back of the doping system (20) which has been evacuated in advance. 26).

Then, impurities such as water, silicon fluoride, and hydrogen fluoride remain, and only ultra-high purity silane is vaporized, resulting in (26).

This second container is heated at -65 to -110°C, preferably -7
The container is maintained at 5 to -100°C, for example -90'C, and the container is used as a collutocinop without liquefying the ring silane, and the water and silicon fluoride in the ring silane are similarly removed in this 1-lap. May be removed.

The semiconductor reactive gas consisting of silane has a flow rate of 31 (29
) to the reaction system ('0). In this reaction system,
~500°C better <ha 250~350eC1 representative ni! A substrate whose surface to be formed is held at 1300° (:) is provided, and the pressure in the reaction area (44) is set at 0.1-10°.
Lorr e.g. 2Lorr, silane flow rate 1-5
For example, 50cc was supplied for 7 minutes. Infrared light 10.6. Light irradiation was performed using a lamp (length: 680 nm, 15 mm, maximum output: 450 W) that emits light with long wavelengths of S or longer. This was also possible using a carbon dioxide laser. Next, the electrical energy is transmitted to a high frequency oscillator (frequency ¥113.56 MIIz)
In addition to the pair of (5) and (6) from (4), the plasma tuna discharge was reduced to -U to carry out 1] PCVD reaction.

The surface of the substrate is placed parallel to the irradiation light for the photochemical reaction, and the photochemical reaction is preheated to 150 to 350'C, for example 300'C, by a flying Haken lamp rather than on the substrate surface. This was done for a reactive gas that has been

By doing this, it is possible to prevent the irradiated light from being hidden behind the substrate and not irradiating the reactive gas on the opposite side.
[Yen that can be mass produced] oLo CVD has been implemented. Furthermore, in the device of the present invention, the reactive gas is preheated to approximately the same temperature as the substrate, and the heated reactive gas is excited by light, so that a film can be formed sufficiently even if the surface of the substrate is not irradiated with light. It also has the advantage of being possible.

In the device of the present invention, electrical energy was added in addition to the optical energy and thermal energy.

At this time, the substrate was disposed in the positive column area of the generated glow discharge, and a silicon crotch was formed on the surface to be formed, for example, the glass substrate, by Fusto Plus Tuna.

The growth rate of this semiconductor film is 0.1~o for Photo CVll only, 3R/sec For example, 0.271/
It was seconds. In addition, in r'pcvo, it was possible to provide 30 times faster growth of 6 to 15 people/second, for example, 12 people/second.

In other words, in the PlIoto CVD method, the substrate surface is not damaged by plasma, so it is possible to obtain a good 1II
However, the growth rate of 11'X' is extremely slow, at 0.1 to 0.3. has.

Although some damage caused by the plasma of the PPCVD method in the present invention is avoided, the growth rate of the target jIQ is 7 Halo -15A/sec, Pl+oLo CVD method) 3
We were able to achieve 0x faster growth. This r'T'c
In the VD method, the sequence of steps is to apply thermal energy to a reactive gas and first irradiate it with light, and a part of the reactive gas is photoexcited and becomes extremely ionized.
, followed by the addition of electrical energy to produce a plasma reaction is extremely important. By doing so, it was possible to prevent a plasma shock wave at the start of discharge, and substantially prevent a plasma reaction on the substrate surface.

As described above, an egg-heavy crystal semiconductor having silicon as a main component and having an oxygen concentration of 1×10 cm or less, as shown by the method of the present invention, could be formed on the surface to be formed.

Note that the remaining impurities deposited in the second container such as water, silicon fluoride, and other impurities that cannot be trapped at temperatures below -65'C are removed after the semiconductor film is formed.
In Fig. 2, the valves (33) and (25) are closed, the valves (34) and (14) are opened, the second container is heated with the heater (39), and the mechanical two-scoop pump (17) is heated. It was evacuated using a vacuum pump (18).

Examining the film quality of this silicon film, we found that the oxygen concentration was less than 1y10aLom/cc (light output 2.0aLom/cc or less) in SIMS measurements.
KW or less, discharge cuff was 0W or less).

Furthermore, if the discharge output is 15W, 2 xl Oato
m/cc and further reduced to 115, connecting the conventionally known silane to the doping system and Photo C
It is produced by VD method or PPCVD method, and the oxygen content in the film is 71! iBelto, 3xlOatom/cc
It was found that the value was reduced to about 1/100 of the Kono value.

In the device of the present invention, the substrate temperature is set to 350'C1400'
By adding C, the crystallinity of the film formed further progressed.

In the PPCVD method, the temperature for producing this reaction product is 3.
It was possible not only at 00'C but also at 150'C to 300'C.

In the r'boto CVD method, the film growth rate is extremely low when monosilane is used as a reactive gas, and industrial improvements have been sought.

The silane is not the above-mentioned monosilane, but a purified monosilane, and this silane is modified by a non-polar discharge method to synthesize a low-oxygenated polysilane (for example, Siゎ11□, -). Semiconductor-grade +
When producing 1Q, the growth rate of the film could be increased to 0.6 A/sec, three times that of monosilane.

Furthermore, if the concentration of nonsine is 75% or more, it will be further reduced to 0.
．． It was possible to set the value to 1 to 0.6λ.

Figure 3 shows how a 0.5 silicon semiconductor layer is deposited on a glass substrate using the apparatus shown in Figure 2 using the PPCVD method (light output 1.OKW, (4
2 mW/co: ) The discharge output was 15 W).

Furthermore, a silicon nitride insulator was laminated on this upper surface as a barrier layer for preventing oxidation to a thickness of 500λ using the same reaction apparatus shown in FIG. Thereafter, a portion of this silicon nitride was removed, and an ohmic contact electrode was provided in this portion as a parallel electrode, and the electrical conductivity characteristics were investigated.

FIG. 3 shows wrinkles using specifically purified silane according to the method of the present invention. Electrical properties of semiconductors (56), <64).

((i5), (66), ([i8), conventional characteristics (57), (63).

(58), (67), and <69> are shown.

In the drawing, in the conventional example, the region (59) exhibits a dark electrical conductivity (57) and has a value of the order of ~10 (-[cm2). Here AMI (100mW/c
m) in the area (60), the conventional method produces a curve (
58) had a value of 1X10 (fLcm), and the value had deteriorated by about one order of magnitude after continuous irradiation for 2 hours.

On the other hand, the semiconductor film produced by the PPCVD method of the present invention has approximately conductivity (56) of 5X'IO (JLcm).
and its optical conductivity (64) is 2X10 (fLcm
) and a fumeteosensitivity of 10, which is about two orders of magnitude larger than that of the conventional example.Furthermore, when irradiated with continuous light, there is almost no deterioration in its electrical conductivity, as seen in curve (65). I couldn't see it.

Furthermore, in the present invention, in the region (61), the conductivity after irradiation was also approximately the same within the range of error compared to (66) and (56).

When heating is further performed at 150'C, the curve (6
7) became (69), and there was an apparent change in the above characteristics, and when the region (62) was then irradiated with light again, the deterioration characteristics were observed again.

That is, in the conventional example, the electrical conductivity is small as shown in (67), and deterioration characteristics are observed due to light irradiation.

However, in the present invention, the electrical conductivity changes even without light irradiation.
Almost no change or deterioration of properties was observed with or without thermal annealing, and the photoconductivity and fumetosensitivity (difference between photoconductivity and approximate conductivity) were large, and the approximate conductivity was small.

Similar high reliability characteristics were obtained with a semiconductor film made by r'hoto CVD.

As described above, it has been found that the method of the present invention has the synergistic effect of being able to provide a highly reliable silicon semiconductor layer.

The Photo CVD apparatus of the present invention substantially eliminates the scorch effect (and enables mass production).As a result, r'N or PIN junctions can be used in photoelectric conversion devices, optical sensors, The present invention can be applied to copying machines, insulated gay 1-type field effect semiconductors, and integrated devices thereof, and is considered to be extremely effective industrially.

Example 2 This example shows the case of manufacturing a silicon nitride insulator.

The apparatus was constructed using Figure 2.

Ultraviolet light of 185 nm and 254 nm was used as a light source for photochemical reactions.

In Figure 2, purified silane is obtained from (26) and ammonia is obtained from (25) as N Hh/S i 114 >
50.

As a result, in the CVD method, 0. We were able to create an IA/sec insulating silicon nitride wave HQ. Furthermore, PP
In the CVD method, a film growth rate of 3/l/sec could be obtained at a substrate temperature of 300° C. and a pressure of 1 torr using the same electrician Nellkey output as in Example 1.

As a result of forming a film with a thickness of 100 OA on a silicon single crystal semiconductor substrate and examining the c-v characteristics, it was possible to obtain an interfacial charge density of 1〆lQ'cin' or less in both cases. Furthermore, even when an electric field intensity of 2'lOV/cm was applied, a hysteresis phenomenon was observed in the CV characteristics, and it was found that the semiconductor surface was hardly sputtered (tU gJ).

Example 3 This example is an example in which a silicon oxide film was produced using the apparatus of the present invention. The apparatus is the same as in Example 2.

Using sulfur instead of ammonia as the reactive gas (25
) was introduced. Add silane (26) to N, O/
It was introduced as S i H4>20. The results obtained were similar to Example 2. Furthermore, it had a dielectric strength of 1×IOV/cm.

Example 4 This example is a case where indium tin (ITOi) (insium oxide containing 10% by weight or less, for example 5% by weight) of tin oxide was formed.

The same equipment as in Example 2 was used. As a reactive gas (2
Indium chloride was added from 6), and NO was added from (25). Furthermore, in order to lower the SEE resistance of the indium oxide formed from (24), soot tetrachloride was added,
Furthermore, nitrogen was added as a carrier gas from (27).

Thus indium oxide or ITO is
0''C, for example, could be obtained at 300°C.

Film formation speed is 7A/sec IL by PPCVD method.
It could be made at 300'C.

The sheet resistance is 20fi10 with a film thickness of 500λ. The transmittance was 87%.

Example 5 In this example, a transparent conductive film of tin oxide was produced.

The equipment was the same as in Example 4.

Soot chloride is used as a reactive gas (24), and Np is used as a reactive gas (24).
5), it was added as Nρ/SnCl+>20.

At the same time, CF3Br was added from (26) to lower the sheet resistance to 50 fL/CI or less (for a thickness of 100 OA).

The formed film was further exposed to irradiation light for photochemical reaction for 50 minutes in an atmosphere or a mixed atmosphere of oxygen and nitrogen.
It was fired at 0°C.

In this way, it was possible to obtain tin oxide having acid resistance and plasma resistance. This tin oxide rib can be placed on a transparent insulating substrate such as a glass substrate, or it can be laminated as a coating on ITO on a glass substrate shown in Example 1 (300 to 1500 person), 5nOL (200~
It was also effective as a 21m1 structure of 400A).

As is clear from the above description, the present invention allows reactive gas to flow downward from above, and the substrates are spaced vertically (vertically) at intervals (3 to 10
They are placed with their backs facing each other with an opening of 5 cm (for example, 5 cm).

Furthermore, in order to prevent one substrate from being in the shadow of another substrate, the surface of this substrate is irradiated with light in parallel to optically excite the reactive gas while it is flying.As a result, the embodiments of the present invention As shown in the figure, 20 20cm x 60cm substrates or 1 5-inch silicon substrate.
00 wafers can be inserted, making it possible to produce 20 times as many 5-inch wafers as in the conventional method, which is believed to have an extremely large industrial effect.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a conventional FO1-CVD apparatus. FIG. 2 shows an outline of a CVD apparatus using the method of the present invention. FIG. 3 shows electrical conductivity characteristics obtained by the method of the present invention and the conventional example. Patent applicant) Koma C Muhi) Grass? tco

Claims (2)

[Claims] While holding the substrate under a reduced pressure of 1.1 atmospheres or less, a reactive gas is introduced from one side along the formation surface of the substrate and discharged from the other side, and the reactive gas is supplied parallel to the formation surface. A photo-CVD apparatus characterized in that a light source for a photochemical reaction of a reactive gas is provided. While holding the substrate under a reduced pressure of 2.1 atmospheres or less, a reactive gas is introduced from one side along the formation surface of the substrate and discharged from the other side, and the reactive gas is supplied parallel to the formation surface. A light source for a photochemical reaction of the reactive gas is provided, and a pair of capacitively coupled light sources are provided for directing an electric field for a discharge plasma along the formation surface for supplying electrical energy to the reactive gas. A photo-CVD apparatus characterized in that an electrode is provided. 3. In claims 1 and 2, the reactive gas is supplied from above to below, and a plurality of substrates each having a surface to be formed are arranged vertically in parallel or approximately in parallel at regular intervals. An optical CVD device characterized by the following.