JPS6312378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film forming apparatus that forms a film on a substrate such as a semiconductor by photochemical reaction.

Conventionally, as a film forming apparatus of this type, there has been one shown in a vertical cross-sectional view in FIG. Reference numeral 1 denotes a closed container made of quartz material that transmits light, and is provided with a reaction gas introduction pipe 2 and a vacuum exhaust pipe 3. Reference numeral 4 denotes a receiving seat provided in the airtight container 1, on which the semiconductor substrate 7 is placed.
Put on. Reference numeral 5 designates a light source such as a mercury lamp, which projects light that causes a photochemical reaction, and reference numeral 6 designates a reflecting plate that surrounds the back side of this light source and reflects the light to the inside of the sealed container 1.

Thin film formation using the above-mentioned conventional apparatus was performed as follows. After evacuating the inside of the container 1, as a reaction gas,
For example, a monosilane such as S _i H ₄ is introduced. Light is projected from the light source 5 and irradiates onto the semiconductor substrate 7 inside the container 1. In this way, the reactive gas undergoes a photochemical reaction, and a thin film, for example, an amorphous silicon film, is formed on the semiconductor substrate 7. By selectively irradiating with light, a thin film with a predetermined pattern can be formed.

In the conventional device described above, amorphous silicon also adheres to the inner wall of the sealed container 1, blocking the transmission of light, and as a result, the speed at which the thin film is deposited on the semiconductor substrate 7 is extremely slow. It had the drawback of causing unevenness.

In this invention, the container is divided into three parts: a light source chamber, a gas introduction chamber, and a photochemical reaction chamber, the wall of the light source chamber is made into an oval reflecting surface with the light source as the focal point, and a partition plate that transmits light from the light source is installed in the light source chamber. and the gas introduction chamber, the lower part of the gas introduction chamber is focused at another focal point of the elliptical surface of the light source chamber, the substrate is placed lower inside the photochemical reaction chamber connected to the lower part of the gas introduction chamber, and the gas is introduced. An inert gas is introduced into the chamber to cover the bottom side of the partition plate, so that the reactive gas introduced from above into the photochemical reaction chamber is blown out downwards, efficiently irradiating light from the light source, and entering the photochemical reaction chamber. Prevents light attenuation,
The object of the present invention is to provide a film forming device using a photochemical reaction that increases the film formation speed, makes the film thickness uniform, improves productivity, and facilitates inspection and repair.

FIG. 2 is a schematic longitudinal sectional view of a film forming apparatus according to an embodiment of the present invention. Reference numeral 10 denotes a light source that causes a photochemical reaction, and is composed of, for example, a mercury lamp. Reference numeral 11 denotes an upper enclosure body which has an elliptical surface with one focal point at the position of the light source 10, has a mirror-finished inner wall surface as a reflective surface, and surrounds the upper and side peripheries to form the light source chamber 12. It is made of metal material. Become. An intermediate enclosure 13 is airtightly connected to the lower part of the upper enclosure 11 via an O-ring 16, and is made of a metal material.
is formed. The gas introduction chamber 14 is gradually narrowed down at the middle portion thereof to form a throttle hole portion 15.
It is located at the other focal point of the elliptical surface of the light source chamber 12, and this aperture hole has a size _t2 that is approximately the same as the diameter _t1 of the light source 10. Reference numeral 17 denotes a partition plate airtightly attached to the upper part of the gas introduction chamber 14 via an O-ring 18, which separates the light source chamber 12 and the gas introduction chamber 14.
It is made of a material, such as a quartz plate, that transmits light of a wavelength used for photochemical reactions that is irradiated from the light source chamber 12. 19 is gas introduction chamber 1
In the upper gas introduction pipe provided on the upper side of 4,
An inert gas such as argon or nitrogen is introduced from the outside to generate an airflow toward the lower surface of the partition plate 17. Reference numeral 20 denotes an intermediate gas introduction pipe provided below the throttle hole 15 of the gas introduction chamber 14, through which an inert gas similar to the pipe 19 is introduced from the outside;
Blows out downward. Reference numeral 21 denotes a reaction gas introduction pipe provided below the gas introduction chamber 14, which has a ring shape, for example, and is used to carry a reaction gas that undergoes a photochemical reaction, such as S _i
H ₄ is introduced from the outside and blown out from multiple outlets provided at the bottom. A lower enclosure 22 is airtightly connected to the lower part of the intermediate enclosure 13 via an O-ring 24, and is made of metal or the like and forms a photochemical reaction chamber 23. 25 is photochemical reaction chamber 2
3, which is made of metal and has a heater 26 built into it. Reference numeral 27 denotes a susceptor made of quartz or the like on the pedestal 25, on which the semiconductor substrate 7 is placed. This substrate 7 is irradiated with light emitted from the light source chamber 12 and passed through the aperture hole 15 forming the other focal point, and a thin film is formed on the upper surface by reactants generated by a photochemical reaction. Reference numeral 28 denotes exhaust pipes installed on both sides of the pedestal 25 at the bottom of the photochemical reaction chamber 24, and before introducing the inert gas and the reaction gas,
The gas introduction chamber 14 and the photochemical reaction chamber 24 are evacuated to a vacuum state, and during the introduction of the inert gas and the reaction gas, the reaction gas is evacuated so as to maintain the reaction gas at a predetermined pressure.

In the apparatus of the above embodiment, the reaction gas is blown downward from the introduction pipe 21 into the evacuated photochemical reaction chamber 24, diffuses onto the substrate 7, and flows toward the exhaust pipe 28. Further, the lower surface of the partition plate 17 is always covered with the inert gas introduced from the upper introduction pipe 19, and is prevented from coming into contact with the reaction gas. The inert gas from the intermediate introduction pipe 20 is blown downward, driving the reaction gas downward. In this way, the irradiated light from the light source chamber 12 is transmitted through the partition plate 17 without being attenuated and irradiated onto the substrate 7, the reaction gas undergoes a photochemical reaction, and a thin film is formed on the substrate 7.

In the above embodiments, a semiconductor substrate is used as the substrate, but the present invention is not limited to this and can be applied to other types of substrates.

Moreover, although the case where the film formed on the substrate is a thin film has been described, the present invention can also be applied to a case where the film is a thick film.

Further, the type of film is not limited to a semiconductor film, and may be an insulating film or a metal film.

Furthermore, in the above embodiment, the gas introduction pipe 20 in the middle part was provided in the gas introduction chamber 14, but if the rise of the reaction gas can be prevented only by the inert gas from the gas introduction pipe 19 in the upper part, the gas Introduction piping 20
may be omitted.

Note that FIG. 2 shows a longitudinal section of an apparatus according to an embodiment of the present invention, and the shape of the side cross section does not have to be the shape shown in FIG. 2, but may be an appropriate shape depending on the situation. In other words, if a bar lamp is used as the light source,
With respect to the longitudinal direction of the lamp, the light source chamber and the circular reflecting surface extend in the longitudinal direction, and the intermediate enclosure and the aperture hole extend in the longitudinal direction.

As described above, according to the present invention, the light source chamber, the gas introduction chamber, and the photochemical reaction chamber are divided into three parts, and the light source chamber and the gas introduction chamber are partitioned by a partition plate that transmits light from the light source chamber, and the gas introduction chamber is divided into three parts. The inert gas introduced into the introduction chamber covers the bottom side of the partition plate, and the reaction gas introduced below the gas introduction chamber is blown out downward and directed toward the substrate placed at the bottom of the photochemical reaction chamber. The inner wall surface of the light source is an elliptical reflecting surface with the light source as the focal point, and the middle of the gas introduction chamber is focused at the other focal point of the elliptical reflecting surface of the light source chamber, so the projected light from the light source is attenuated. The irradiation is transmitted through the partition plate without any problems, and compared to conventional methods, the film formation speed is faster, productivity is improved, and the film thickness can be made uniform to improve quality. In addition, since the chamber is divided into three parts: a light source chamber, a gas introduction chamber, and a photochemical reaction chamber, inspection and repair are easy.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing a conventional film forming apparatus, and FIG. 2 is a schematic vertical cross-sectional view showing a film forming apparatus according to an embodiment of the present invention. 7... Substrate, 10... Light source, 11... Upper enclosure, 1
2... Light source chamber, 13... Intermediate enclosure, 14... Gas introduction chamber, 15... Diaphragm hole portion, 17... Partition plate, 19...
Gas introduction piping, 20...Intermediate gas introduction piping, 21
...Reaction gas introduction pipe, 22... Lower enclosure, 23...
Photochemical reaction chamber, 25... pedestal, 28... exhaust piping. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A light source that projects light that causes a photochemical reaction in a reactive gas, which surrounds the top and sides of this light source, and whose inner wall surface is an elliptical reflective surface with the light source as one focal point. an upper enclosure forming a light source chamber; the upper enclosure is airtightly connected to the lower part of the upper enclosure, and at the other focal point with respect to the oval reflecting surface, the middle part is narrowed to approximately the same size as the light source; An intermediate enclosure is provided with an aperture hole to allow the projected light from the light source and the reflected light from the reflective surface to pass downward, and forms a gas introduction chamber; a partition plate that is airtightly attached and partitions the light source chamber and the gas introduction chamber and that transmits the irradiated light from the light source chamber, and is disposed in the intermediate enclosure at a position above the aperture hole; A gas introduction pipe for introducing an inert gas from the outside and covering the lower side of the partition plate, airtightly connected to the lower part of the intermediate enclosure, surrounding the substrate on the lower pedestal, and forming a photochemical reaction chamber. a lower enclosure to be formed, a reaction gas introduction pipe arranged below the gas introduction chamber, which introduces a reaction gas from the outside and blows it out downward to fill the area above the substrate; A film forming apparatus using a photochemical reaction, which is provided with an exhaust pipe for sucking out a part of the gas in the photochemical reaction chamber and maintaining the pressure at a predetermined pressure. 2. The film forming device by photochemical reaction according to claim 1, wherein the partition plate is made of a quartz plate. 3. The intermediate enclosure is equipped with an intermediate gas introduction pipe near the bottom of the throttle hole, which blows out inert gas from the outside and prevents the reaction gas from rising. A film forming apparatus using a photochemical reaction according to claim 1.