JPH0341724A - Vertical type vapor growth apparatus - Google Patents

Abstract

PURPOSE:To increase the flow speed of a raw gas as the gas moves downward by movably connecting the upper end parts of a plurality of adjusting plates to the inner wall surface of a reacting tube so that the adjusting plates can be inclined in the direction of the diameter of the reaction tube, and providing a large slant angle. CONSTITUTION:Adjusting plates 16 are arranged along the inner sidewall surface of a reaction tube 2 so as to surround the outer surface of a susceptor 4. The respective adjusting plate 16 has the same curvature as that of the reaction tube 2. The upper end part of each adjusting plate 16 is movably connected to the inner side wall surface of the reaction tube 2 with an attaching metal fixture 18 so that the plate 16 is inclined in the direction of the diameter of the reaction tube 2. When the adjusting plate 16 is inclined to the side of the susceptor 4, the cross sectional area of the part through which a gas stream passes is decreased in the downward direction. As a result, the flow speed of the raw gas is increased as the gas flows downward.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vertical vapor phase growth apparatus, and particularly relates to a vertical vapor growth apparatus improved to achieve uniform film thickness distribution. It is something.

[Prior Art] Semiconductor crystal films are widely used as crystal materials for photoelectronic devices and ultrahigh-speed electronic devices. FIG. 4 is a schematic diagram of a conventional vertical vapor phase growth apparatus.

The vertical vapor phase growth apparatus includes a vertical cylindrical reaction tube 2 .

Inside the cylindrical reaction tube 2, a barrel-shaped susceptor 4 having an inclined surface and a spherical upper portion is installed.

A semiconductor substrate 6 is held on the inclined surface of the susceptor 4 .

The susceptor 4 rotates in the direction of arrow R within the cylindrical reaction tube 2 . A raw material gas introduction nozzle 8 for introducing raw material gas into the cylindrical reaction tube 2 is provided at the apex of the cylindrical reaction tube 2 . In addition, in the lower part of the cylindrical reaction tube 2,
An exhaust port 14 is provided for exhausting exhaust gas.

A cooling pipe 10 is attached to the side wall of the cylindrical reaction tube 2 so as to surround the side wall of the cylindrical reaction tube 2. Cooling water flows into the cooling pipe 10. Further, a high frequency coil 12 is arranged so as to surround the cylindrical reaction tube 2.

Next, a method for growing a semiconductor crystal film using this apparatus will be described.

The semiconductor substrate 6 is held on the inclined surface of the susceptor 4, and the susceptor 4 is rotated in the direction of arrow R. Next, high frequency coil 1
2 is ONL, and the susceptor 4 is heated to a predetermined temperature by high frequency induction. Thereafter, the raw material gas (for example, trimethyl gallium, As
Introduce H3). Then, the source gas causes a reaction such as thermal decomposition, and a GaAs crystal film is grown on the semiconductor substrate 6 disposed on the inclined surface of the susceptor 4. The raw material gas is
Thereafter, it is discharged to the outside through the exhaust port 14.

Since cooling water is flowing through the cooling pipe 10 provided on the wall of the reaction tube 2, consumption of raw material gas on the wall of the reaction tube 2 is suppressed. Further, the reason why the side wall of the susceptor 4 has an inclination angle is to make the film thickness distribution uniform in the gas flow direction. Further, the reason why the susceptor 4 is rotated at a predetermined rotation speed is to prevent the influence of one-sided flow of the introduced raw material gas.

[Problems to be Solved by the Invention] Now, in the conventional vertical vapor phase growth apparatus, the inclination angle of the side wall of the susceptor 4 and the distance between the susceptor 4 and the reaction tube 2 (that is, the cross-sectional area through which the gas flow passes) Decisions are made through flow visualization experiments and computer simulations before equipment design, as well as through trial-and-error experiments using actual equipment.

Conventionally, this method was used to make the film thickness distribution uniform in the gas flow direction.

However, at present, there is a demand for a higher degree of uniformity in film thickness distribution, etc. Under such current circumstances, the method of improving the above-mentioned device structure is practically
It's not that easy.

In addition, as another method, a method has been proposed in which the film thickness distribution and the like are made uniform by changing the growth conditions such as the total gas flow rate, but this method has limitations due to the relationship with other characteristics.

This invention was made to solve the above-mentioned problems, and aims to provide a vertical vapor phase growth apparatus that can uniformize the film thickness distribution in the gas flow direction using a simple method. purpose.

[Means for Solving the Problems] The present invention relates to a vertical vapor phase growth apparatus that flows a source gas from top to bottom and grows a decomposed product of the source gas as a semiconductor crystal film on a substrate.

The vertical vapor phase growth apparatus is equipped with a vertical cylindrical reaction tube into which source gas is introduced. A susceptor is provided in the vertical cylindrical reaction tube to hold the substrate on its inclined surface.

A plurality of adjustment plates are arranged along the inner wall surface of the vertical cylindrical reaction tube so as to surround the susceptor. The upper ends of the plurality of adjustment plates are movably connected to the inner wall surface of the reaction tube so that the adjustment plates can be tilted in the radial direction of the reaction tube. By increasing the inclination angle of this adjustment plate, the flow velocity of the raw material gas increases as it goes downward. Furthermore, the vertical vapor phase growth apparatus is equipped with an inclination angle adjusting means for adjusting the inclination angle of the adjustment plate.

The adjusting plate used in the present invention preferably has the same curvature as the inner wall surface of the reaction tube.

The same applies to the shape of the attachment portion of the adjustment plate.

Further, it is preferable that the plurality of adjustment plates be arranged without any gaps along the inner wall surface of the reaction tube.

[Effect]

The vertical vapor phase growth apparatus according to the present invention includes a plurality of adjustment plates that increase the flow velocity of the source gas downward by increasing the angle of inclination thereof.

The inclination angle of the adjustment plate can be easily adjusted by operating the inclination angle adjusting means. Therefore, by operating the inclination angle adjusting means, it is possible to easily increase the flow rate of the raw material gas by 1 as it goes downward.

[Length Example 1 Hereinafter, examples of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic diagram of a vertical vapor phase growth apparatus according to an embodiment of the present invention. The embodiment shown in FIG. 1 is similar to the conventional example shown in FIG. 4 except for the following points, and the same parts are given the same reference numerals and the explanation thereof will be omitted.

In the embodiment shown in FIG. 1, six adjustment plates 1 shown in FIG.
6 are arranged along the west side wall surface of the reaction tube 2 so as to surround the susceptor 4 .

Each adjusting plate 16 has a shape having the same curvature as the reaction tube 2. The upper end of each adjustment plate 16 is rotatably connected to the inner wall surface of the reaction tube 2 by a mounting bracket 18 so that the adjustment plate 16 can be tilted in the radial direction of the reaction tube 2.

Referring to FIG. 2, the adjustment plates 16 arranged on the inner wall surface of the reaction tube 2 are sequentially numbered with ■■...■.The adjustment plate ■■■ is the adjustment plate ■■■ It is installed so that it is located outside of the A rectangular hole 2 is provided at the bottom of the adjustment plate 16.
4 are provided, and adjacent adjusting plates 16 are fixed to each other without any gaps by the fittings 20. And 1
By moving the cutting adjustment plate■■■, the adjustment plate■■
■It can also be moved. An adjusting screw 22, which is an inclination angle adjusting means for adjusting the inclination angle of the adjusting plate 16, is provided on the outside of the reaction tube 2. The tip of the adjustment screw 22 is connected to a fitting. The inclination angle of the adjustment plate 16 is adjusted from the outside of the reaction tube 2 by operating the adjustment screw 22 through the fitting 20.

Next, the principle of making the film thickness etc. uniform by attaching the adjusting plate 16 will be explained.

FIG. 1 shows the state when the adjustment plate 16 is tilted toward the susceptor 4 side. By tilting the adjusting plate 16 toward the susceptor 4 as shown in the figure, the susceptor 4 and the adjusting plate 16 (which can be considered as a newly formed wall surface of the reaction tube) are formed.

), the distance decreases as you go downwards. As a result, the cross-sectional area of the portion through which the gas flow passes decreases as it goes downward. As a result, the flow velocity of the raw material gas increases as it goes downward. That is, tilting the adjustment plate 16 toward the susceptor 4 as shown in the figure means that the fourth
In the conventional device shown in the figure, the result is the same as that of substantially changing the inclination angle of the side wall portion of the susceptor 4, and the film thickness distribution in the gas flow direction is improved.

In addition, in this embodiment, the upper end of the adjustment plate 16 is processed to have the same curvature as the reaction tube 2, so even if the adjustment plate 16 is moved, no gap will be generated in this part, causing turbulence in the gas flow. occurrence is prevented.

Next, the effects of the device according to the example will be explained while showing a specific example. An example will be explained in which a GaAs crystal film is epitaxially grown on a 2-inch GaAs substrate. The inner diameter of reaction tube 2 is 30 cm s and the height is 50 cm.
The inclination angle of the m′-susceptor 4 was set to 6°. TMG (trimethyl gallium) and AsH were flowed into the reaction tube 2 from the raw material gas introduction nozzle 8 together with the H2 carrier gas.

The flow rate is 7M020cc, AsH, ISLM (Sta
ndard 1 liter/m1nute), H2 carrier gas 19SLM. Growth pressure is 70To
r r, the growth temperature was 650°C.

The thickness distribution of the obtained GaAs crystal film in the gas flow direction is
As shown in the figure. Film thickness (%) is based on the film thickness on the upstream side (100
%).

Curve (b) is the result when the adjustment plate 16 is not moved (in other words, when the wall angle of the new wall surface is 0). As shown in the figure, the film thickness decreased from upstream to downstream, and the variation was 14.3%. Note that the variation in film thickness was determined by the following formula.

Curve (a) is the result when the adjusting plate 16 is moved by the adjusting screw 22 so that the adjusting plate 16 has an inclination of 3° with respect to the wall surface of the reaction tube 2. In this case, the variation in film thickness distribution in the gas flow direction was 3.1%.

[Effects of the Invention] As explained above, according to the vertical vapor phase growth apparatus according to the present invention, by increasing the inclination angle, the flow velocity of the source gas can be increased in the downward direction. Since it is equipped with two adjustment plates, by manipulating these, it is possible to easily improve the uniformity of the film thickness distribution in the gas flow direction.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a vertical vapor phase growth apparatus according to an example. FIG. 2 is a perspective view of a plurality of adjusting plates used in the vertical vapor growth apparatus according to the embodiment. Figure 3 shows
FIG. 3 is a diagram showing the film thickness distribution in the gas flow direction of a GaAs crystal film obtained using the apparatus according to the example. FIG. 4 is a schematic diagram of a conventional vertical vapor phase growth apparatus. In the figure, 2 is a cylindrical reaction tube, 4 is a susceptor, 6 is a semiconductor wafer, 8 is a nozzle for introducing raw material gas, 16 is an adjustment plate, 18 is a mounting bracket, 20 is a fitting, and 22 is an adjustment screw. . In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A vertical vapor phase growth apparatus for flowing a raw material gas from top to bottom and growing a decomposed product of the raw material gas as a semiconductor crystal film on a substrate, the vertical type into which the raw material gas is introduced. a cylindrical reaction tube; a susceptor provided in the vertical cylindrical reaction tube and holding the substrate on its inclined surface; and their upper ends are rotatably connected to the inner wall surface of the reaction tube so that the adjustment plate can be tilted in the radial direction of the reaction tube, and by increasing the angle of inclination, a plurality of adjustment plates that increase the flow velocity of the raw material gas in a downward direction; an inclination angle adjustment means that adjusts the inclination angle of the adjustment plates;
Vertical vapor phase growth equipment equipped with