JPS6393109A - Vertical type vapor growth device - Google Patents

Abstract

PURPOSE:To obtain uniform semiconductor crystals of large area by a method wherein a rectifyer, with which reaction gas will be rectified, is provided in the center part inside a gas introducing part, and the susceptor of a wafer, having the aperture to be used to pass reaction gas in the center part, is provided in a reaction chamber. CONSTITUTION:The area of a gas conveying path 1 is formed smaller than the area of a reaction chamber 3 on the route from the gas conveying path 1 to a substrate supporting stand 5a. Also, in a gas introducing path 2, the cross-sectional area on which gas flows is made small by a rectifier 4. Accordingly, the flow speed of gas reaching the substrate supporting stand 5a is increased, the effect of heat convection is removed, and as there is no space where reaction gas stagnates, the switching of reaction gas can be performed at high speed. Also, gas can be blown against the substrate supporting stand 5a uniformly by forming the cross-sectional shape of the reaction gas stream and the substrate supporting stand 5a in doughnut shape.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vertical vapor phase growth apparatus suitable for the vapor phase growth of gallium arsenide or a compound semiconductor layer containing gallium arsenide as a main component, and particularly relates to a mass production type apparatus thereof. It is related to.

[Conventional technology]

FIG. 2 shows a cross-sectional structure of a conventional vertical vapor phase growth apparatus. (wafer)
6 is a heating RF coil that heats the susceptor 5 , 7 is a support rod that supports and rotates the susceptor 5 , 10 is a gap between the susceptor 5 and the side wall of the reaction chamber 3 It is.

Next, the operation will be explained.

The susceptor 5 provided in the reaction chamber 3
is heated by induction by an RF coil 6 located around the .

At this time, the reaction gas sent from the gas transport path 1 passes through the gas introduction part 2, reaches the semiconductor wafer (semiconductor substrate) placed on the susceptor 5, and is thermally decomposed to form semiconductor crystals on the surface of the semiconductor wafer. grow. Furthermore, the reaction gas passes through the gap 1o between the susceptor 5 and the side wall of the reaction chamber 3, and is exhausted downward. During the growth, the susceptor 5 is rotated by the rotation of the support rod 7 to improve the uniformity of crystal growth in the direction of rotation.

[Problem that the invention seeks to solve]

Because the conventional vertical vapor phase growth apparatus is configured as described above, the distance between the semiconductor substrate placed on the susceptor 5 and the gas transport path 1 that transports the gas is quite large. As a result, heated gas near the substrate rises upward, causing thermal convection and causing the following problems.

First, a uniform flow of reaction gas within the reaction chamber 3 is prevented, resulting in non-uniformity in the thickness of the grown film. Secondly, the heated and reacted gas flows back to the upper part of the reaction chamber 3 and contaminates the gas inside the reaction chamber 3, thereby degrading the quality of the crystal. Thirdly, since the volume of the reaction chamber 3 up to the substrate is large and the reaction gas cannot be replaced quickly, there is also the problem that it is not possible to make a sharp change in the crystal film properties in the growth direction. These problems become more pronounced as the inner diameter of the reaction chamber 3 increases, so the processing capacity of a conventional vertical vapor phase growth apparatus is generally 1.
The growth has been limited to less than one 2-inch wafer,
This was a factor that made it impossible to increase mass production.

This invention was made to solve the above-mentioned problems, and provides a mass-produced vertical vapor phase growth apparatus that can grow a large number of semiconductor crystals of uniform thickness and high quality over a large area. It is aimed at something.

[Means for solving problems]

In the vertical vapor phase growth apparatus according to the present invention, a rectifier for rectifying the reaction gas is provided in the center of the gas introduction section, and a susceptor having an opening for passing the reaction gas in the center of the reaction chamber is provided. It is something that

[Effect]

In the present invention, a rectifier for rectifying the reaction gas is provided in the center of the gas introduction section, and a wafer susceptor having an opening for passing the reaction gas is provided in the reaction chamber, so that the gas transport path is In addition, the gas flow path in the gas introduction part can be made sufficiently thin to achieve a high-speed gas flow, which can prevent thermal convection and change the gas composition rapidly.Furthermore, it is possible to blow a reactant gas flow with a doughnut-shaped cross section onto the susceptor. This allows a gas flow to be generated uniformly over a wide area on the susceptor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a vertical vapor phase growth apparatus according to an embodiment of the present invention. In the figure, 1 is a gas transport path, and 2 is a gas transport path 1 with a small diameter to a reaction chamber 3 with a large diameter. This is a gas introduction part for introducing gas, and this has a truncated conical shape with an inner diameter that becomes wider toward the downstream side. Reference numeral 4 denotes a flow rectifier placed at the center of the gas introduction section 2. This rectifier and the inner wall of the truncated conical gas introduction section 2 form a gas flow with a doughnut-shaped cross section in the gap 8 between the two. A reaction gas is blown onto a donut-shaped substrate support 5a having an opening. Here, the gap 9 between the rectifier 4 and the substrate support stand 5, and the gap 10 between the inner wall of the reaction chamber 3 and the substrate support stand 5a, are constructed so that their cross-sectional areas are no longer approximately equal. Gas is uniformly blown onto 5a. A support rod 7 supports the substrate support stand 5a, and rotates during growth to improve the uniformity of crystal growth in the direction of rotation. 6 is an RF coil for heating the substrate support.

Next, the effects will be explained.

In such a configuration, the substrate support 5 is connected to the gas transport path 1.
In the path leading to a, the area of the gas transport path 1 is equal to that of the reaction chamber 3.
In addition, in the gas introduction section 2, the cross-sectional area through which the gas flows is reduced by the rectifier 4. Therefore, the gas flow rate reaching the substrate support stage 5a is several times higher than that of the conventional apparatus, eliminating the influence of thermal convection, and since there is no space for reaction gas to stagnate, switching of reaction gases can be performed at high speed.

FIG. 4 shows the change in composition when GaAs is grown and then the reaction gas is switched to continuously grow an Aj2GaAS film using the apparatus of this embodiment, compared with the case using the conventional apparatus. In the conventional device, the composition changes gradually due to the backflow of the reaction gas due to thermal convection and gas stagnation, as shown in FIG. 4 (al), and a steep interface cannot be obtained. A steep compositional change as shown in FIG. 4(b) becomes possible.

Further, the gas that reaches the heated substrate support 5a is thermally decomposed here, and a semiconductor crystal grows on the substrate placed on the support 5. At this time, in the conventional apparatus, the gas that reaches the support As the diameter increases, the gas flow becomes non-uniform, resulting in a distribution in the thickness of the grown film outward from the center of the support (see Figures 3 (al) and (b)). On the other hand, in the apparatus of this embodiment, the cross-sectional shape of the flow of the reaction gas and the substrate support
By making the shape of a into a donut shape, the substrate support stand 5
Since the gas can be uniformly blown onto the substrate support 5a and the area of the gap 9 at the center of the substrate support 5a is approximately equal to the area of the gap 10 outside the substrate support 5a, Gas flows evenly in and out.

As a result, even though the device is a large device capable of mounting a large number of substrates, it is possible to obtain film thickness uniformity for each substrate that is equivalent to or better than that of a small device (see FIG. 3 (see C1)).

Furthermore, in this example device, the gas flow is high-speed and no thermal convection occurs, so problems such as deterioration of crystal quality due to reaction products in the gas phase, contamination of the upper inner wall of the reaction chamber, and falling rings of contaminants do not occur. .

〔Effect of the invention〕

As described above, according to the vertical vapor phase growth apparatus according to the present invention, a rectifier for rectifying the reaction gas is provided in the center of the gas introduction section, and a flow rectifier for passing the reaction gas through the center of the reaction chamber is provided. Since a wafer susceptor having openings is provided, it is possible to obtain a uniform and high quality semiconductor crystal over a large area.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a vertical vapor phase growth apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional vertical vapor growth apparatus, and FIG. 3 is a view showing film thickness distribution. FIG. 4 is a diagram showing changes in composition. DESCRIPTION OF SYMBOLS 1... Gas conveyance path, 2... Gas introduction part, 3... Reaction chamber, heather 4... Rectifier, 5... Substrate support stand, 6... RF coil, 7... Support Rod, 8... Gap between gas introduction part and rectifier, 9... Gap between rectifier and substrate support, 10.
...Gap between the substrate support stand and the wall of the reaction chamber. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) It has a gas transport path, a truncated conical gas introduction part, and a reaction chamber, and the reaction gas sent from the gas transport path is passed through the gas introduction part to the reaction chamber whose diameter is larger than that of the gas transport path. In the vertical vapor phase growth apparatus, the reaction gas is introduced into the reaction chamber and reacted with the wafer in the reaction chamber. A vertical vapor phase growth apparatus comprising: a susceptor for a wafer having an opening for passing the reaction gas. (2) Vertical vapor phase growth according to claim 1, characterized in that the opening area of the opening in the susceptor of the wafer is approximately equal to the cross-sectional area of the gap between the susceptor and the inner wall of the reaction chamber. Device.