JPH05175136A - Optical cvd apparatus - Google Patents

Abstract

PURPOSE:To obtain a uniform film-thickness distribution, while a substrate is not rotated, by partially arranging flow guard plates, which are equipped at a flow guard member in the title apparatus, on the gas inlet side from the center of the substrate. CONSTITUTION:The top wall of a reaction chamber 21 is provided with a light transmission window 28 in the position facing a substrate 23, a synthetic quartz jet plate 32 having many small holes is provided under the inside surface of the light transmission window 28, and a flow guard member 34 is attached to the underside of the synthetic quartz jet plate 32 for jetting inert gas. In the flow guard member 34, flow guard plates 36 are mounted at 10mm spaces only on the upstream side from the center of the substrate 23. Each flow guard plate 36 extends in the direction of crossing the flow of the reaction gas from a nozzle 25 and also directs the inert gas jetted from the quartz jet plate 32 downward of the substrate 23 on a susceptor 22. In an apparatus constituted in this manner, the concentration of the reaction gas works in the direction where it is made uniform so that the film-thickness distribution of the substrate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus used for manufacturing semiconductors, liquid crystal displays and the like.

[0002]

2. Description of the Related Art In recent years, silane,
Development of an optical CVD apparatus that decomposes a compound gas such as disilane to form a thin film on a silicon wafer or a glass substrate has been actively made. An optical CVD apparatus using such light can be processed at a low temperature and does not cause deterioration of a substrate or a formed film due to charged particles, and thus has attracted a great deal of attention as a next-generation device manufacturing method. However, in such an optical CVD apparatus, there is a big problem that the reaction product stains the light transmission window and the surface of the lamp, and the light amount is reduced. In order to deal with such a problem, for example, as disclosed in JP-A-60-209248, the reaction chamber and the light source chamber are partitioned by a UV-permeable porous plate, and an inert gas is passed through the porous plate. It has been proposed to prevent contamination of the light transmission window and the surface of the lamp by purging. However, an optical CVD apparatus that employs only such a simple gas flow method under reduced pressure is effective when performing a film formation process for a relatively short time on a substrate with a small area of an experimental machine level, but When a film is deposited for a long time on a production machine level device that processes an area substrate, film deposition on the perforated plate becomes apparent, and the amount of light greatly decreases as the production time increases. This is a fatal problem when considering stable and reproducible mass production.

In order to address the above-mentioned problems, the present inventors have further studied the drawbacks of the above-mentioned conventional type device, and, as previously proposed in Japanese Patent Application No. 3-84043, in the conventional type device. Under the UV transparent perforated plate, newly,
This problem was completely solved by arranging a flow guard member comprising a number of flow guard plates extending parallel to the axis of each small hole formed in the perforated plate and spaced apart from each other.

FIG. 4 is a cross-sectional view showing an example of the photo-CVD apparatus previously proposed by the present inventors, and FIG. 5 is a perspective view of an essential part thereof. In FIG. 4, reference numeral 1 is a reaction chamber in which a temperature-variable susceptor 2 is provided.
The substrate 3 is mounted on the top. The side wall of the reaction chamber 1 is provided with a nozzle 5 having a thin slit-shaped opening 4 for introducing the first gas, that is, the reaction gas.
Is connected to the external introduction pipe 6. An exhaust port 7 is provided at one end of the bottom wall of the reaction chamber 1. On the upper wall of the reaction chamber 1, a light transmitting window 8 made of synthetic quartz is provided at a position facing the substrate 3, and a light source 9 emitting a wavelength suitable for a photochemical reaction is provided outside the light transmitting window 8 and a loss of light. A reflector 10 for preventing the
A light source chamber 11 that houses these is attached. Further, below the inner surface of the light transmitting window 8, an ejection plate 12 having a large number of small holes made of synthetic quartz is provided with a slight gap between the inner surface of the light transmitting window 8 and the inner surface. The space formed by the light transmission window 8 and the ejection plate 12 having a large number of small holes made of synthetic quartz is connected to the conduit 13 and serves as an inlet for the inert gas which is the second gas.

A flow guard member 14 is attached to the lower side of the jet plate 12 for jetting the above-mentioned inert gas, and the flow guard member 14 is, as shown in FIG. The flow guard plates 16 made of a thin synthetic quartz plate are attached at regular intervals, and FIG. 5 shows an example in which 11 sheets are attached.
Each of the flow guard plates 16 extends in a direction transverse to the flow direction of the reaction gas from the nozzle 5, and the conduit 13
The inert gas introduced from the jet plate 12
It is oriented downwards towards the substrate 3 on the susceptor 2. Therefore, each flow guard plate 16 in the flow guard member 14 can be set arbitrarily according to the inner size of the reaction chamber 1 and the like.

In operation, first, the reaction gas is introduced from the external conduit 6 through the thin slit-shaped opening 4 of the nozzle 5 into a sheet shape substantially parallel to the surface of the substrate 3. On the other hand, the inert gas with respect to the flow of the sheet-like reaction gas is discharged from the ejection plate 12
It is introduced further and is guided downward to the substrate 3 by the flow guard frame body 15 of the flow guard member 14 and the flow guard plate 16. By the downward flow of the inert gas directed by the flow guard member 14 in this manner, the flow of the sheet-like reaction gas from the nozzle 5 is effectively suppressed in the vicinity of the substrate 3, and thus the introduced reaction gas The generation and diffusion of turbulence are effectively suppressed, and as a result, it is possible to completely prevent the reaction products from adhering to the surfaces of the light transmission window 8 and the ejection plate 12, and to achieve stable film formation for a long time. Become.

[0007]

The photo-CVD apparatus configured as described above is very excellent in that it completely prevents the reaction products from adhering to the surfaces of the light-transmitting window and the inert gas ejection plate. However, when a film is formed on a large-diameter substrate, there is a problem that the film thickness distribution, particularly the distribution in the flow direction of the reaction gas, is extremely poor.

FIG. 6 is a film thickness distribution diagram in the direction parallel to the flow when an amorphous silicon film is formed on a 6-inch substrate by using the photo CVD apparatus shown in FIG. It is understood that the film is deposited only on the most upstream side, that is, about 50% of the first gas inlet side. This is because while the reaction gas flows from the inlet port toward the exhaust port, the inert gas for purging from above is mixed to dilute the reaction gas, and a large concentration gradient is introduced from the inlet port to the exhaust port. It is presumed to occur. As a means for improving such distribution, generally, a method of rotating the susceptor 2 on which the substrate 3 is mounted is widely used. However, if dust is generated from the sliding portion due to rotation, or if a heating mechanism devised to obtain uniform temperature distribution of the substrate is mounted on the susceptor, it is hard to rotate the susceptor 2. There are problems such as being extremely difficult. Further, even if the substrate can be rotated, if the average value of the film thicknesses of the most upstream and the most downstream is larger or smaller than the film thickness at the center of the substrate, the substrate is rotated to obtain a uniform film thickness distribution. Is impossible. Therefore, in consideration of these situations, an apparatus capable of depositing a film without rotating the substrate and obtaining a uniform distribution is required.

An object of the present invention is to solve the above-mentioned problems and to provide an optical CVD apparatus for a large-diameter substrate at a greige level.

[0010]

In order to achieve the above object, the photo-CVD apparatus of the present invention comprises a reaction chamber for accommodating a substrate to be processed, and means for introducing and exhausting a reaction gas into the reaction chamber. A light source for photochemically reacting the reaction gas to form a thin film on the substrate, a light source chamber for housing the light source, and light having a large number of small holes between the reaction chamber and the light source chamber. A permeable gas ejection plate and a flow guard member provided under the ejection plate, the flow guard member having a plurality of flow guard plates extending parallel to the axis of each small hole formed in the ejection plate and spaced from each other, are arranged. Introducing a first gas flow in a sheet form from a gas inlet port substantially parallel to the surface of the substrate housed in the reaction chamber, and introducing a second gas from the direction perpendicular to the surface to the surface on the substrate. Flow is introduced from the gas ejection plate, and further below the gas ejection plate. A flow guard provided in the flow guard member in an optical CVD apparatus configured to maintain the first gas flow in a laminar state near the surface of the substrate by passing the provided flow guard member. It is characterized in that the plate is partially arranged from the center of the substrate to the first gas introduction port side.

[0011]

In the photo-CVD apparatus according to the present invention configured as described above, since the flow guard plate of the flow guard member is arranged only upstream from the center of the substrate, that is, on the side of the first gas inlet, the inert gas is not used. The purging effect due to is strong on the upstream side from the center of the substrate and weak on the downstream side from the center of the substrate. From another viewpoint, this means that the dilution effect of the inert gas is strong from the center of the substrate to the upstream side, while weakened from the center of the substrate to the downstream side. Therefore, the reaction gas is diluted more strongly on the upstream side where the reaction gas concentration is relatively high, and when viewed from the whole, the reaction gas concentration is made uniform and the film thickness distribution of the substrate is improved.

Further, since the flow guard plate is arranged on the upstream side where the reaction gas concentration is high, the surface of the light transmission window or the surface of the inert gas ejection plate is similar to the photo CVD apparatus proposed by the present inventors. There is no problem of adhesion of reaction products to the.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of an optical CVD apparatus for a large-diameter substrate showing an embodiment of the present invention, and FIG. 2 is a perspective view of a flow guard member used in this embodiment.

In the figure, reference numeral 21 denotes a reaction chamber, a susceptor 22 whose temperature is controlled at 250 ° C. is provided inside the reaction chamber, and a 6-inch glass substrate 23 is provided on the susceptor 22.
Is installed. A nozzle 25 having a thin slit-shaped opening 24 for introducing a reaction gas is provided on the side wall of the reaction chamber 21, and the nozzle 25 is provided with an external introduction pipe 26.
Is connected with. An exhaust port 27 is provided at one end of the bottom wall of the reaction chamber 21. Further, on the upper wall of the reaction chamber 21, at a position facing the substrate 23, the diameter is 300 mm and the thickness is 15 m.
m synthetic quartz light transmission window 28 is provided, and a low pressure mercury lamp 29 and a reflection plate 30 for preventing light loss are provided on the outside thereof.
And a light source chamber 31 for accommodating them is attached. Further, below the inner surface of the light transmitting window 28, a space of 10 mm is provided between the inner surface of the light transmitting window 28 and a large number of small holes having a diameter of 0.6 mm, and a size of 200 mm × 3.
An ejection plate 32 made of synthetic quartz and having a diameter of 00 mm is provided. The space formed by the light transmission window 28 and the synthetic quartz ejection plate 32 serves as an inlet for an inert gas that is a second gas and is connected to the conduit 33.

On the other hand, a flow guard member 34 is attached to the lower side of the synthetic quartz ejection plate 32 for ejecting an inert gas, and the flow guard member 34 has a thickness of 30 mm as shown in FIG. In a flow guard frame 35 of size 200 mm x 300 mm, thickness 1 mm, size 200
The flow guard plate 36 made of a synthetic quartz plate having a size of 30 mm × 30 mm is provided 10 mm only upstream from the center of the substrate 23.
It is installed at intervals. Each flow guard plate 36 extends in a direction transverse to the flow direction of the reaction gas from the nozzle 25 and directs the inert gas ejected from the quartz ejection plate 32 downward toward the substrate 23 on the susceptor 22. Oriented.

In the apparatus constructed as described above, silane and mercury vapor are used as the reaction gas, and argon gas is used as the inert gas. Further, the flow guard plate 36 is arranged at an interval of 10 mm from the most upstream side of the flow guard frame 35. Sheets, 4
The film thickness distribution when depositing an amorphous silicon film on a 6-inch size glass substrate was determined for each of the configurations of one, six, and eight.

FIG. 3 is a diagram showing the measurement result of the film thickness distribution in the direction parallel to the flow of the reaction gas. As can be seen from this figure, the film thickness distribution greatly changes depending on the number of flow guard plates, and in the apparatus of this embodiment, the film thickness distribution within ± 5% was obtained when the number of flow guard plates was four.

In this embodiment, the best film thickness distribution was obtained when four flow guard plates were mounted at intervals of 10 mm from the most upstream side as described above. However, depending on the reaction gas used and the size of the substrate, Since the film thickness distribution changes, the number and place of the flow guard plates to be mounted or the mounting intervals are not limited to this. Depending on the experimental conditions at that time, the number of mounted sheets or the mounting interval may be increased or decreased, or the mounting location on the flow guard frame may be changed. Further, during the experiment of this example, the reaction products did not adhere to the surface of the light transmission window or the inert gas ejection plate.

[0019]

As described above, according to the present invention,
By disposing the flow guard plate of the flow guard member only on the upstream side from the center of the substrate, that is, on the side of the first gas introduction port, adhesion of reaction products to the surface of the light transmission window or the inert gas ejection plate occurs. Without doing so, a uniform film thickness distribution can be obtained without using the substrate rotating mechanism, and the productivity can be greatly improved with a good yield.

[Brief description of drawings]

FIG. 1 is a sectional view of a photo-CVD apparatus showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of a flow guard member used in the photo CVD apparatus of the present invention.

FIG. 3 is a film thickness distribution characteristic diagram in a direction parallel to the flow of the reaction gas obtained in the example of the present invention.

FIG. 4 is a cross-sectional view of a conventional photo-CVD apparatus.

FIG. 5 is a perspective view of a flow guard member showing a conventional example.

6 is a film thickness distribution characteristic diagram in the direction parallel to the flow of the reaction gas obtained by the apparatus of FIG.

[Explanation of symbols]

 21 Reaction Chamber 22 Susceptor 23 Glass Substrate 24 Slit-shaped Opening 25 Nozzle 26 External Introducing Tube 27 Exhaust Port 28 Synthetic Quartz Light Transmission Window 29 Low Pressure Mercury Lamp 30 Reflector 31 Light Source Chamber 32 Synthetic Quartz Spout Plate 33 Conduit 34 Flow Guard Member 35 Flow guard frame 36 Synthetic quartz flow guard plate

Claims (1)

[Claims] 1. A reaction chamber for accommodating a substrate, means for introducing and exhausting a reaction gas into the reaction chamber, and a light source for photochemically reacting the reaction gas to form a thin film on the substrate. A light source chamber for accommodating the light source, a light-transmissive gas ejection plate having a large number of small holes between the reaction chamber and the light source chamber, and small holes formed in the ejection plate below the ejection plate. Arranging a flow guard member provided with a large number of flow guard plates extending parallel to the axis and spaced from each other,
A first gas flow is introduced into a sheet form from a gas introduction port substantially parallel to the surface of the substrate housed in the reaction chamber, and a second gas flow is introduced onto the surface of the substrate from a direction perpendicular to the surface. Is introduced from the gas ejection plate and further passed through the flow guard member provided under the gas ejection plate, so that the first gas flow is maintained in a laminar state near the surface of the substrate. In the photo-CVD apparatus described above, the flow-guard plate included in the flow-guard member is partially arranged from the center of the substrate to the first gas introduction port side.