JPH11340153A - Vapor-phase growth system for compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor-phase growth system capable of obtaining a good quality crystal being efficiently and easily produced. SOLUTION: In a device for growing a vapor-phase of compound semiconductor thin film with the use of an organometal compound gas, an introduction pipe 12 covering over a susceptor 21 mounting a wafer and introducing an reactive gas on the wafer 50 on which the compound semiconductor thin film is grown is provided. At least an internal area 24 of the gas introduction pipe 12 where a reactive product is produced with reactive gas is made rough. The reaction product strongly attached to the rough internal area does not drop on the wafer. This makes it possible to reduce the cleaning frequency of the introduction pipe 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for vapor-phase growth of a compound semiconductor. In particular, the present invention relates to an apparatus having an introduction pipe for guiding a gas to a substrate on which a crystal is to be grown, and to an apparatus having a longer period until replacement of the introduction pipe which can perform high-quality crystal growth.

[0002]

Conventionally, a metal organic chemical vapor deposition (hereinafter referred to as "MOVPE"), gallium nitride compound semiconductor _{(Al X Ga y In 1-} xy N; 0 ≦ x ≦ 1,0
≤ y ≤ 1, 0 ≤ x + y ≤ 1) A vapor phase growth of a thin film on a sapphire substrate and a light emitting device using the gallium nitride based compound semiconductor thin film have been studied.

Since a single crystal wafer of a gallium nitride-based compound semiconductor cannot be easily obtained, a gallium nitride-based compound semiconductor has been epitaxially grown on a sapphire substrate having a lattice constant similar to that of the single crystal wafer.

However, when a gallium nitride-based compound semiconductor is grown on a sapphire substrate with a different material and a different lattice constant, crystal growth is difficult, and subtle disturbance of the reaction gas immediately leads to lattice defects. In the case of vapor-phase growth of a gallium nitride-based compound semiconductor, a group V element,
That is, the decomposition temperature of ammonia (NH ₃ ), which is a source of nitrogen (N), is high. As a result, the balance of the stoichiometry is easily lost, and it is difficult to obtain a uniform large-area crystal film. In order to obtain a uniform large-area crystal film, it is necessary to increase the flow rate without disrupting the laminar flow of the reaction gas. For this reason, it is necessary to use a shape as described in JP-A-2-29113. An introduction tube containing a substrate is used.

[0005]

However, the temperature of the introduction tube becomes high due to the heating of the substrate, the reaction gas reacts near the inner wall of the introduction tube, and a reaction product adheres to the inner wall of the introduction tube. There is a problem that an object falls or flies and adheres to the substrate. For this reason, in order to maintain a uniform crystal, it was necessary to remove and clean the inlet tube after several crystal growths. For this reason, there was a problem that the production efficiency of the crystal was poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a vapor phase growth apparatus capable of obtaining homogeneous crystals with high production efficiency.

[0007]

According to an aspect of the present invention, there is provided an apparatus for vapor-phase growing a compound semiconductor thin film using an organometallic compound gas, comprising a step of covering a susceptor on which a substrate is mounted with a reactive gas. Is introduced to the upper portion of the substrate on which the compound semiconductor thin film is grown, and at least the inner surface of the introduction tube where a reaction product is generated by the reaction gas is roughened.

The invention according to claim 2 is that the region to be roughened is the inner surface of the introduction pipe above the substrate.
The invention of the present invention is that the region to be roughened is the inner surface of the introduction pipe which is heated to a high temperature by heating. Further, according to the invention of claim 4, the height difference between the peaks and valleys of the rough surface is 1 μm to 100 μm.
The range is characterized by.

[0009]

According to the first aspect of the present invention, since at least the inner surface of the region of the introduction pipe where the reaction product is generated is formed as a rough surface, the surface area increases and the reaction product adheres. Even so, detachment becomes difficult because the adhesion strength increases. Therefore, it is possible to efficiently prevent the reaction product from adhering to the substrate due to the reaction product falling onto the substrate or flying on the substrate. As a result, the number of times of cleaning the introduction tube is reduced, and the time that can be used for crystal growth until the next cleaning or replacement is increased. Therefore, it is possible to provide a manufacturing apparatus capable of obtaining a highly efficient, easily manufactured, and homogeneous crystal.

According to the second aspect of the present invention, the above effect can be effectively achieved by making the inner surface of the introduction pipe above the substrate rough.

Similarly, according to the third aspect of the present invention, since the inner surface of the introduction pipe, which is heated to a high temperature by heating, is roughened, it is possible to efficiently prevent the reaction products generated at the high temperature from falling. . Therefore, the above effects can be effectively achieved.

According to the fourth aspect of the present invention, the height difference between the peaks and valleys of the unevenness of the rough surface is in the range of 1 μm to 100 μm, so that the separation of the reaction product can be easily prevented. If it is less than 1 μm, there is no effect of preventing separation of reaction products, and if it is more than 100 μm, laminar flow is disturbed, which is not desirable. 1 to
The most desirable result is obtained in the range of 20 μm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. In FIG. 1, the quartz tube 10 is sealed at its left end with an O-ring 15 and abuts against the flange 14.
And nuts 48, 49, etc., are fixed to the flange 14 at several places. The right end of the quartz tube 10 is an O-ring 40.
And screwed to the flange 27 with screw fasteners 41, 42
It is fixed by.

In an inner chamber 11 surrounded by a quartz tube 10, an introduction tube 12 for introducing a reaction gas is provided. The introduction pipe 1
2 is held at one end 13 on the gas inlet side by a holding plate 17 fixed to a flange 14, and at the bottom 1 of the other end 16.
Reference numeral 8 denotes a holding leg 19 which is held by the quartz tube 10. And the introduction pipe 12 is inclined in the -Z direction.

The cross section of the introduction tube 12 perpendicular to the long axis (X axis) of the quartz tube 10 differs depending on the position in the X axis direction as shown in FIGS. 2 to 5, and its plan shape is shown in FIG. So that it is enlarged as it proceeds downstream. That is, the reaction gas flows in the X-axis direction, but the cross section of the introduction pipe 12 is circular as shown in FIG.
(Positive axis direction), the ellipsoidal shape is enlarged in the long axis direction and reduced in the short axis direction with the Y axis direction as the long axis, and the susceptor 20 is placed at the slightly upstream position A in FIG. As shown in the figure, the shape is a flat elliptical shape that is thin in the vertical direction (Z axis) and long in the Y axis direction. IV- at position A
The length of the opening in the Y-axis direction in the sectional view taken in the direction of the arrow IV is 7
cm, and the length in the Z-axis direction is 1.2 cm. The position A constitutes a throttle portion of the introduction pipe 12.

A sample mounting chamber 2 having a rectangular cross section perpendicular to the X axis, on which the susceptor 20 is mounted, is provided downstream of the inlet tube 12.
1 are integrally connected. The susceptor 20 is mounted on the bottom 22 of the sample mounting chamber 21. The susceptor 20
Has a rectangular cross section perpendicular to the X axis, but its upper surface 23 is gently inclined in the positive direction of the Z axis with respect to the X axis. A sample, that is, a rectangular sapphire substrate 50 is placed on the upper surface 23 of the susceptor 20.
And the gap between the upper pipe wall 24 of the introduction pipe 12 and the facing pipe wall,
It is 12 mm at the upstream part of the sapphire substrate 50 and 4 mm at the downstream part. A guide portion is formed by the upper tube wall 24 and the gap.

An operation rod 26 is connected to the susceptor 20. The flange 27 is removed, and the susceptor 20 on which the sapphire substrate 50 is mounted is placed in the sample mounting chamber 21 by the operation rod 26, and the susceptor 20 is used for crystal growth. When the process is completed, the susceptor 20 can be taken out of the sample mounting chamber 21.

Further, a first gas pipe 28 and a second gas pipe 29 are opened on the upstream side of the introduction pipe 12. First gas pipe 2
8 is inside the second gas pipe 29 and both pipes 28,
Reference numeral 29 denotes a coaxial double tube structure. First gas pipe 28
A large number of holes 30 are formed in the peripheral portion of the portion not covered by the second gas pipe 29, and a large number of holes 30 are also formed in the second gas pipe 29. Then, the reaction gas introduced by the first gas pipe 28 is blown into the introduction pipe 12, and is mixed therewith for the first time with the gas introduced by the second gas pipe 29.

The first gas pipe 28 is connected to the first manifold 3
1 and the second gas pipe 29 is connected to the second manifold 32.
It is connected to the. The first manifold 31 has a supply system I for carrier gas (H ₂ , N ₂ ) and a supply system J for trimethylgallium (Ga (CH ₃ ) ₃ ) (hereinafter referred to as “TMG”).
And trimethyl aluminum (Al (CH ₃ ) ₃ ) (hereinafter “TMA”
Supply system K) and silane (SiH ₄ ) supply system L
And a supply system M of cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) (hereinafter referred to as “CP ₂ Mg”), and trimethylindium (In (CH ₃ ) ₃ (hereinafter referred to as “TMI”). ) Is connected to the supply system O. The second manifold 32
An NH ₃ supply system H and a carrier gas supply system I are connected.

A cooling pipe 33 for circulating cooling water is formed on the outer periphery of the quartz tube 10, and a high-frequency coil 34 for applying a high-frequency electric field is provided on the outer periphery.

The introduction pipe 12 is connected to an external pipe 35 via a flange 14, and a carrier gas is introduced from the external pipe 35. In the sample mounting chamber 21, an introduction pipe 36 extends from the outside through the flange 14 from the side, and a thermocouple 43 for measuring the temperature of the sample and its conductors 44 and 45 are provided in the introduction pipe 36. Is provided so that the sample temperature can be measured from the outside.

With such an apparatus configuration, the first gas pipe 2
8, the mixed gas of TMG, TMA and TMI if necessary, the mixed gas of silane or CP ₂ Mg and H ₂ as needed, and the mixed gas of NH ₃ and H ₂ guided by the second gas pipe 29 The mixed reaction gases are mixed near the outlets of the tubes, and the mixed reaction gas is guided to the sample mounting chamber 21 by the inlet tube 12 and passes through a gap formed between the sapphire substrate 50 and the upper tube wall 24 of the inlet tube 12. I do. At this time, the flow of the reaction gas on the sapphire substrate 50 is made uniform in the Y direction by the action of the throttle portion at the position A, and is also made uniform in the X direction by the action of the guide portion by the upper tube wall 24 covering the sapphire substrate 50. A laminar flow is obtained. As a result, a high-quality crystal with little place dependence on the substrate grows.

The above-mentioned introduction tube 12 is provided with a sapphire substrate 50.
The upper tube wall 24 corresponding to the upper part on which is mounted is strongly heated, and this part becomes high temperature. In this embodiment, the inner surface of the upper tube wall 24 is roughened by sandblasting 60. As a result, the reaction product attached to the inner surface of the upper tube wall 24 was prevented from dropping onto the sapphire substrate 50. When the inner surface was not roughened, it was necessary to replace the introduction tube 12 every three to six times of crystal growth to remove and clean the products attached to the inner surface. However, by roughening the inner surface as described above, it is sufficient to replace and clean the introduction pipe 12 every 15 to 20 times of crystal growth, thereby extending the time span for cleaning. .

In the above embodiment, the sapphire substrate 50
Although the roughening is performed only on the inner surface of the upper tube wall 24 located above, the roughening may be performed on the entire inner surface of the introduction pipe 12.

Modifications 1) Although the introduction tube 12 is made of quartz glass, it may be made of metal. 2) The gas was supplied to the sapphire substrate 50 from the horizontal direction. However, even when the gas was supplied from the vertical direction, the inner wall of the introduction pipe may be roughened. 3) The heating method is not limited to the high frequency heating, but may be a resistance heating method. 4) In particular, when high-frequency heating is performed, it is efficient to perform roughening on the inner surface of the portion where the temperature of the introduction pipe 12 is high, because of the processing time and the effect. 5) The method of rough surface processing may be sand blasting, sand paper, plasma etching, chemical etching, or the like. 6) The cross-sectional shape of the introduction pipe 12 is arbitrary. 7) The introduction tube 12 may be configured to house the susceptor 21 inside as in the embodiment, or may be formed in a lid shape that covers only the upper portion of the susceptor 12. In this case, susceptor 2
Leakage of the reactant gas is prevented on the upper surface of the first member. 8) The substrate is not limited to a sapphire substrate;
iC or GaN may be used. 9) The composition ratio and type of the crystal to be vapor-phase grown on the substrate are not limited. However, it is particularly effective for vapor phase growth of a compound semiconductor having a high growth temperature such as AlGaInN.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vapor phase growth apparatus according to a specific embodiment of the present invention.

FIG. 2 is a cross-sectional view at each position in an axial direction of an introduction pipe of the device.

FIG. 3 is a cross-sectional view of the introduction tube.

FIG. 4 is a cross-sectional view of the introduction tube.

FIG. 5 is a cross-sectional view of an introduction tube in a portion where a susceptor is placed.

[Explanation of symbols]

10 ... supply system J ... TMG of the quartz tube 12 ... inlet 20 ... susceptor 21 ... sample mounting incubation cabinet 28 ... first gas pipe 29 ... second gas pipe 50 ... supply system I ... carrier gas of the sapphire substrate H ... NH ₃ K: TMA supply system L: Silane supply system O: TMI supply system

Claims (4)

[Claims] 1. An apparatus for vapor-phase growing a compound semiconductor thin film using an organometallic compound gas, comprising: an introduction pipe that covers a susceptor on which the substrate is mounted and guides a reaction gas to an upper portion of the substrate on which the compound semiconductor thin film is grown. An apparatus for vapor-phase growth of a compound semiconductor, wherein an inner surface of at least a region of the introduction pipe where a reaction product by the reaction gas is generated is roughened. 2. The compound semiconductor vapor deposition apparatus according to claim 1, wherein the region to be roughened is an inner surface of an introduction pipe above the substrate. 3. The compound semiconductor vapor phase growth apparatus according to claim 1, wherein the region to be roughened is an inner surface of the introduction pipe which is heated to a high temperature by heating. 4. A height difference between peaks and valleys of a rough surface is 1 μm to 1 μm.
The compound semiconductor vapor deposition apparatus according to claim 1, wherein the thickness is in a range of 00 μm.