JPH0362514A - Vapor growth device - Google Patents

Abstract

PURPOSE:To deposit a thin film in even thickness and composition on a substrate by a method wherein multiple exhaust ports are provided on the downstream of a gas flow from the substrate position in a reaction part so as to regulate the exhaust resistance using a needle valve and flow rate controlled compensation gas. CONSTITUTION:Reactive gas led in from a gas leading-in port 5 is reacted to a substrate 6 on a graphite-made holding base 1 induction-heated by high-frequency coils 8 so as to deposit a crystal and then reactive gas is exhausted from multiple exhaust ports 2 of an exhaust means 3. An exhaust pressure regulator 9 rough-regulates the pressure of exhaust gas 90 by a needle valve 91 and then feeds compensating gas for microadjustment control. Due to the pressure regulation, the gas flow near the substrate is optimized so that the thickness and the composition of thin film may be equalized.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is directed to thin films from gas phase to solid state, such as Si. Ge, crystals such as compound semiconductors, Si, 2. Au, O,. Regarding equipment for growing insulators such as Si3N4 on substrates,
In particular, the present invention relates to a vapor phase growth apparatus with good yield when used for devices.

[Conventional technology]

A gas phase reaction apparatus for growing a thin film on a substrate is widely used particularly for forming semiconductor thin films because of its mass productivity and good controllability. Among them, GaAs and InP are used for semiconductor lasers and photodetectors. MOCVD for growing compound semiconductors such as InGaAs
The device is attracting attention as it can produce thin films of better quality than liquid phase growth devices. However, in this apparatus, full-scale mass production technology has not been established unlike the prior art Si CVD due to problems such as side reactions of raw materials and adhesion of products to the inner walls of the reaction chamber. In particular, there is a strong demand for improving the thickness and composition distribution of the grown thin film within the plane of the substrate to improve yield. A conventional device related to the present invention is disclosed in Japanese Unexamined Patent Application Publication No. 1988-61.
There is a device described in Japanese Patent No.-101492. This device has a partial exhaust port near the height of the board, but there is no mechanism to adjust the exhaust coverage with the lower exhaust port. Therefore, the gas flow near the substrate is disturbed, and an auxiliary mechanism such as a substrate rotation mechanism is required to improve the in-plane distribution.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, in order to reduce the in-plane distribution of the substrate and obtain a uniformly grown film, a mechanism for rotating and revolving the substrate and a mechanism for rotating the gas introduction part are provided in the reaction chamber. However, it is necessary to perform axis adjustment, position setting, inspection, repair, etc. of the power transmission section and rotating section, and each time it is necessary to take measures such as stopping the device and opening the reaction chamber to outside air. The object of the present invention is to provide a vapor phase growth apparatus that can grow a high-quality, uniform film on a large area substrate without the need for a rotation mechanism or similar auxiliary mechanism for making the grown film uniform. The goal is to provide the following.

[Means to solve the problem]

The apparatus of the present invention is provided with a plurality of exhaust ports, and the exhaust ports are arranged so that the streamline direction of the exhaust gas is at an angle from parallel to perpendicular to the streamline direction of the reaction gas. installed in the pipe. As a result, the flow of the reaction gas is affected by the exhaust force of each exhaust port, and flows in multiple directions. The exhaust force at each exhaust port is controlled by an exhaust force adjustment mechanism provided between the exhaust port and the exhaust pump. Since each adjustment mechanism is independent, the exhaust force of each exhaust port can be changed independently. Therefore, the flow of the reaction gas in the reaction tube can be changed arbitrarily, and the thickness and composition distribution of the grown film can be made uniform without providing a revolution mechanism.

[Operation 1] The principle of operation of the present invention will be explained using FIGS. 1, 2, and 3. FIG. 1 is a cross-sectional view of the reaction tube of the apparatus of the present invention, in which the reaction gas introduced from the gas inlet 5 reacts on the substrate 6 on the graphite support 1 which is heated by induction by the high-frequency coil 8. , grow crystals. The reaction gas is exhausted from a plurality of exhaust ports 2 by an exhaust means 3. The installation of the exhaust port 2 will be explained with reference to FIG. FIG. 2 is a longitudinal sectional view of the reaction section shown in FIG. 1. The exhaust ports 2 are arranged, for example, at equal intervals vertically and horizontally on a plane perpendicular to the gas flow. The reaction gas is exhausted from each of the exhaust ports 2. At this time, the exhaust force at the exhaust port 2 is controlled by the exhaust force 1iljI'I1 mechanism shown in FIG. Next, the exhaust force adjustment mechanism will be explained using FIG. The exhaust force adjustment mechanism 9 of the present invention is composed of a needle valve 91, a flow rate control section 92 for N295 compensation gas, and a pressure gauge 93. First, the pressure of the exhaust gas 90 is coarsely adjusted using the needle valve 91, and then finely adjusted by flowing compensation gas. By adjusting this pressure, the flow of the reactant gas near the substrate can be optimized so that the thickness and composition of the thin film are uniform. Furthermore, by utilizing the above-mentioned effect, it is possible to change the growth rate of the thin film and the gas in the reaction tube without changing the gas flow rate. [Example] Examples of the present invention will be described below with reference to FIGS. 4 to 9. [Example 1] InGaAs was grown. The length of the quartz reaction tube 41 is 500 m+n, and the inner diameter is 50 mmφ. Gas inlet 5
Support rod 7 is located approximately 250m+n away downstream from 1.
There is a graphite support 11 supported by 1. The diameter is 50m1 on the support stand! The six substrates on which the lφ InP single crystal substrate 61 is mounted are heated by induction heating of the graphite support 11 by the high frequency coil 81. As shown in FIG. 5, there are four exhaust ports 21 in the vertical and horizontal cross directions on the wall of the reaction tube downstream from the support table, and the reaction gas is exhausted from these ports by a pump 31. An exhaust force adjustment mechanism 19 is provided between each exhaust port and the exhaust pump 31, and the exhaust force of each exhaust line can be changed independently. On the other hand, 40cc of A s H3 was used as the reaction gas for the growth phase.
/min, TEG 0.5cc/min, TEI 0.2cc/min
The mixture was supplied from the gas inlet 51 into the reaction tube 41 in an H2 atmosphere. At the same time, the crystal substrate 61 was heated to 650° C. and growth was performed for 1 hour. When the in-plane distribution of the film thickness and composition was measured after the growth was completed, the former was ±20% and the latter was ±2%. next,
Only the exhaust coverage of each exhaust port was adjusted so that each exhaust force was equal, that is, the pressure in the exhaust force adjustment mechanism 19 was equal, and growth was performed again under the same gas introduction and temperature conditions. The resulting film had a thickness distribution of ±1% and a composition distribution of ±0.1%, both of which were significantly improved. In addition, under the same gas introduction conditions and growth temperature as above, growth was performed by increasing only the exhaust force at the bottom of the reaction tube among the four exhaust ports, and the film growth rate was the same as before the balance change. It's now half. This is because a biased flow of the reaction gas occurred in the reaction tube, and the gas flow rate on the crystal substrate 61 decreased. From the above, it can be seen that the apparatus according to the present invention is extremely effective in obtaining a high-quality grown film with a uniform in-plane distribution of thickness and composition. [Example 2] Another example to which the present invention is applied will be described with reference to FIGS. 6 and 7. This example uses a vertical reaction tube, which conventionally requires a substrate rotation mechanism. In this example, InGaAs was grown on an InP crystal substrate 62 in the same manner as in Example 1 using the apparatus shown in FIG. The diameter of the crystal substrate 62 is 50 mmφ. The substrate is heated by induction heating the graphite support 12 using a high frequency coil 82. The exhaust ports 22 are arranged at right angles to each other as shown in FIG. As in Example 1, growth was performed while adjusting the exhaust force of each exhaust port with the exhaust force adjustment mechanism 29, and the in-plane distribution of the InGaAs growth layer was found to be within the thickness ±1%2 composition ±
It became 0.1%. As a result, similar effects were obtained in the vertical tube as in the horizontal tube of Example 1. [Example 3] Another example to which the present invention is applied will be described using FIGS. 8 and 9. In the embodiment shown in this figure, the exhaust ports installed at four locations in the second embodiment are increased to six locations. In addition, each exhaust port 23 is attached at an acute angle, and the attachment to the reaction tube 43 is structured to reduce turbulence in the gas flow at that part. When InGaAs was grown using this apparatus in the same manner as in Example 2, the thickness was ±0.6% and the thickness of the two layers was ±0.04.
A grown layer with an in-plane distribution of % was obtained. The reason why the in-plane distribution was improved compared to Example 2 is that the exhaust port 2
This is because by adding 3, the gas flow on the crystal substrate 63 can be controlled more delicately.

[Effects of the Invention] When the device to which the present invention is applied is used, there is no need to provide an opening mechanism such as a rotation mechanism for the substrate or a rotation mechanism for the reaction gas introduction section.
A film with uniform thickness and composition distribution can be grown on the substrate. Therefore, the yield of device crystals can be improved several times that of conventional devices. Further, since a complicated structure is not required, it is possible to apply the present invention by modifying a conventional device.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a horizontal reaction tube type device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the device, FIG. 3 is a block diagram showing the configuration of the exhaust force adjustment mechanism, and FIG. 4 is a side sectional view of an embodiment in which the shape of the exhaust port of the device shown in FIG. 1 is changed, and FIG.
Figure 6 is a vertical cross-sectional view of the vertical reaction tube type apparatus of the example, Figure 7 is a side view of the apparatus shown in Figure 6, and Figure 8 is an additional exhaust port. FIG. 9 is a longitudinal cross-sectional view of the vertical reaction tube type apparatus of the example, and FIG. 9 is a cross-sectional view of the apparatus shown in FIG. 8. 9.19,29,39...Exhaust force adjustment mechanism, 2.21
, 22, 23...exhaust port. Figure 6

Claims (3)

[Claims] 1. A vapor phase growth apparatus characterized in that a plurality of exhaust ports are provided on the downstream side of the gas flow from the substrate position of the reaction section. 2. 2. An exhaust force adjusting mechanism installed in a vapor phase growth apparatus according to claim 1, wherein exhaust resistance is controlled using a needle valve and a compensation gas whose flow rate is controlled. 3. 2. The vapor phase growth apparatus according to claim 1, wherein the exhaust flow rate of the exhaust port can be changed.