JPH0149004B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is an apparatus for forming a thin film by a photo-excited chemical vapor phase reaction, and the present invention is an apparatus for forming a thin film by photoexcited chemical vapor phase reaction. This invention relates to a CVD (vapor phase reaction) device that forms materials without coating them with oil or the like.

``Prior Art'' A known technique for forming thin films through gas-phase reactions is the optical CVD method, which activates reactive gases using light energy. This method is superior to the conventional thermal CVD method or plasma CVD method in that it is possible to form a film at a lower temperature and does not damage the surface on which it is formed.

However, when implementing such an optical CVD method, an example of which is shown in FIG. ing. The doping system 7 includes a mercury bubbler 21 for excitation of the reactive gas.
And the exhaust system 8 is equipped with a rotary pump. When a reactive gas such as disilane from the doping system is introduced into the reaction chamber 2 and amorphous silicon is formed on the substrate (substrate temperature 250°C), a large amount of silicon is also introduced into the quartz window for transmitting ultraviolet light in the reaction chamber. A film will be formed. Therefore, in order to prevent film formation on this window, this window is thinly coated with Fombrin oil 20.

However, while this oil has the effect of preventing the formation of a film on the window, it also has the possibility of being mixed into the film. The degree of oil coating is very qualitative.

Since the low-pressure mercury lamp is maintained at atmospheric pressure, the atmosphere between the mercury lamp and the quartz chamber prevents ultraviolet light, especially
Short ultraviolet light of 185 nm is absorbed.

When a large window is used to form a large-area substrate, the chamber has disadvantages such as being easily damaged by vacuum.

Therefore, as a countermeasure to this problem, there is a diffusion furnace method as seen in Japanese Patent Application Laid-Open No. 59-68923 "Thin Film Formation Technology". In this forming device, an inert gas is injected from the inside onto the inner wall of the window instead of fomblin oil. This gas can then prevent reaction products from adhering to the inner walls of the quartz. However, in this case, changes in the pressure inside the reactor due to gas supply etc. are extremely delicate, and a large amount of this inert gas must be flowed into the reactor, so the reactive gas is diluted by the inert gas. It has the disadvantage of being stored away.

``Means for Solving the Problems'' In order to solve these problems, the present invention creates a slit in the portion corresponding to the window (with a width of 1 mm or less, generally 0.3
The windows are made into holes (bar-shaped holes, ie, slits) by providing a large number of these slits in parallel as a group. As a result, the adhesion of products to windows is "no window glass"
Therefore, it has the feature that it is essentially impossible.

Furthermore, vacuum the light source room containing the low-pressure mercury lamp (0.1~
10 torr) to reduce absorption loss of 185 nm ultraviolet light. As a result, ultraviolet light was sufficiently supplied to the reaction chamber by condensing the ultraviolet light with a lens and arranging a slit in this condensing portion.

Furthermore, in the apparatus having the structure shown in FIG. 2, a gas that does not constitute a solid product after the reaction, such as N ₂ O, NH ₃ , N ₂ H ₄ , etc., is supplied into the light source chamber,
This made it possible to inject and supply the sufficiently excited and decomposed gas into the reaction chamber through the slit. Another feature is that a mixing reaction of two types of gas can be performed near the surface on which the gas is formed.

``Function'' Due to these characteristics, it was possible to completely prevent the adhesion of reactive gases to the window and the associated decrease in the amount of transmitted ultraviolet light into the reaction chamber.

In addition, by arranging multiple pairs of ultraviolet light sources, lenses, and slits in a sagging pattern, it is possible to
It is now possible to form a film on a 30cm x 30cm substrate without any problems.

``Example'' The present invention will be described in detail below using an example shown in FIG.

In FIG. 2, a substrate 1 having a surface to be formed is placed close to a heater 3 in a reaction chamber 2. As shown in FIG.
The reaction chamber 2 and the light source chamber 5 have approximately the same degree of vacuum, and the exhaust system 8
It is held by vacuuming. The preliminary chamber 4 has a substrate 1' and is separated from the reaction chamber by a gate valve 6.

In the doping system, a reactive gas that becomes a solid product after the reaction of 31 to 33 is supplied to the reaction chamber 2, and 3
A reactive gas or an inert gas that does not become solid after the reaction in steps 4 and 35 is supplied to the light source chamber 5. During the reaction, this gas passes through the slit and reaches the reaction chamber where it reacts and impurities are exhausted.

The light sources include a low-pressure mercury lamp 9, a parabolic reflector on the back, a quartz lens 10 for focusing, and a stainless steel plate 1 with a slit at the focal point of the light focused by this lens.
4 are installed.

Further, the ultraviolet light spreads and the light from adjacent slits are superimposed on each other so that the surface to be formed is irradiated with a uniform light source.

The heater was located above the reaction chamber and was of the "deposition up" type to avoid flakes from adhering to the surface to be formed and causing pinholes.

In addition, the heat from the heater heated the mercury lamp, thereby avoiding the emitted light wavelength from becoming longer due to increased temperature of the mercury lamp. The exhaust system includes a pressure control valve 17, a turbo molecular pump 18,
It consists of a rotary pump 19, and a turbo molecular pump 18 prevents the backflow of oil. The spare room also has a similar structure.

In the drawing, high frequency energy can be simultaneously held between the stainless steel plate having slits and the substrate 1 from a high frequency power source 13.

This enabled the device to be equipped as a CVD device that performs not only photoexcitation but also plasma CVD or photoexcitation and plasma reaction simultaneously.

The reaction chamber was made of stainless steel, and the light source chamber was evacuated. As a result, the present invention does not have the drawback of not being able to withstand pressure when the quartz chamber is enlarged for irradiation of a large area, as shown in the conventional example. That is, the ultraviolet light source is also kept under vacuum in a stainless steel container surrounding a light source chamber and a reaction chamber that are kept under vacuum. Therefore, the size is 40cm instead of 30cm x 30cm.
Boards as large as 120 cm can be made without any industrial problems.

In the case of the drawing, the substrate to be formed is 30cm x 30cm,
The ultraviolet light source was 10 low-pressure mercury lamps (emitting wavelengths of 185 nm and 2547 nm, emission length 40 cm, pressure 80 mW/cm ² , lamp power 400 W). Slit width
0.3mm, length 350mm, slit spacing 30mm, total 400mm
A stainless steel substrate 14 with a width of 10 mm was used. The temperature of the substrate was a predetermined temperature ranging from room temperature to 500°C.

Experimental example 1 Formation example of silicon nitride film Ammonia was used as a reactive gas from 35 to 30c.c./
Disilane was supplied from 33 at a rate of 8 c.c./min, and the substrate temperature was set at 250°C. The substrate is a 30cm x 30cm glass plate. The pressure inside the reactor was 1.5 torr. A film thickness of 1200 Å was formed in 30 minutes of reaction. The film formation rate is 40 Å/min, and direct photoexcitation is used without excitation using mercury vapor deposition or the like. The variation of the 5 points of the coating was within ±5%.

Experimental Example 2 Formation Example of Amorphous Silicon Film Disilane (Si ₂ H ₆ ) was supplied from 33. 34
More krypton was supplied. Helium was also supplied from 35. Krypton was able to form a film with a thickness of 2000 Å on the formation surface in 60 minutes of deposition using pressure excitation.

The substrate temperature was 250°C and the pressure was 1.5 torr.

Experimental Example 3 Formation Example of Silicon Oxide Film Disilane (Si ₂ H ₆ ) was supplied from 33 at a rate of 8 c.c./min.

N ₂ O was supplied from No. 35 at a rate of 30 c.c./min. Then,
N ₂ O sufficiently decomposes the light source chamber into N ₂ and active oxygen,
It was supplied to the reaction chamber and an oxide film with a thickness of 4000 Å was created. A film formation rate of 250 Å/min could be obtained.

Experimental Example 4 Method of forming amorphous silicon by optical plasma vapor phase method The method was the same as Experimental Example 3, and high frequency energy of 13.56 MHz was applied from 13 to 10 W/(30 cm x 30 cm). Even though the same disilane was supplied, a film of 2500 Å could be obtained in 20 minutes. A film growth rate of 170 Å/min was achieved.

"Effects" As is clear from the above description, the present invention is directed to forming a film on a large-area substrate using a windowless apparatus using a slit. This eliminates the need to coat the windows with fomblin oil in the same reactor, and as a result, it has become possible to perform plasma gas phase reactions at the same time.

Although the present invention has shown experimental examples using silicon and silicon oxide, M(CH ₃ ) _o , that is, M
As the material, Al, Ga, In, and B may be used. Also iron,
It is effective to use a carbonylated product of nickel or cobalt as a reactive gas to form a film of iron, nickel, cobalt or a compound thereof.

In the experimental examples described above, the dopant can be added at the same time. It goes without saying that an excimer laser (wavelength: 100 to 400 nm), an argon laser, a nitrogen laser, or the like may be used as a light source instead of a low-pressure mercury lamp.

[Brief explanation of drawings]

FIG. 1 shows an outline of a conventional optical CVD apparatus. FIG. 2 schematically shows a thin film forming apparatus according to the present invention. 2...Reaction chamber, 3...Substrate heating section, 7...Doping system, 8...Exhaust system, 9...Light source.

Claims (1)

[Claims] 1. A thin film forming apparatus using a photo-excited thermochemical reaction, comprising: a rod-shaped light emitting source disposed in a light source chamber; a cylindrical lens; and a slit provided at a position where light is focused by the lens. and a heated substrate having a surface to be formed which is irradiated with the light dispersed in the reaction chamber after condensing the light, and means for supplying a gas from the light source chamber to the reaction chamber in which no solid is generated after the reaction. 2. A thin film forming apparatus comprising: means for supplying a reactive gas that produces a solid after reaction to the reaction chamber; and means for exhausting unnecessary gas from the reaction chamber. 2. In claim 1, a plurality of rod-shaped light sources, a cylindrical lens, and a plurality of slits provided at positions where the light is focused by the lens are provided, and the surface to be formed is irradiated with optical excitation light. A thin film forming apparatus characterized by: 3. The thin film forming apparatus according to claim 1, wherein the surface to be formed is disposed facing the irradiation light.