JPH05221772A - Method and device for producing compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To suppress the generation of crystal defects in the device for producing the AB-type single crystal of zinc blende structure by the boat method by inclining the specified direction of the single crystal provided on the growth surface side of a seed crystal in the specified direction. CONSTITUTION:One direction equivalent to the <100> direction of the AB-type compd. semiconductor single crystal is provided on the growth surface side of a seed crystal, the direction is turned from the seed crystal setting part of a boat toward the bottom surface and inclined to the horizontal direction of the boat through an angle theta of 5-30 deg.. When a GaAs single crystal is grown, for example, one direction A equivalent to the <100> direction of the single crystal 1 is provided on the crystal growth surface side of the seed crystal 1, and a seed crystal is inclined downward to the longitudinal (horizontal) direction of the boat through the angle of theta, formed and set. Consequently, the frequency of generation of twin defects is reduced, and the yield and throughput are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a compound semiconductor single crystal by a boat method such as a horizontal Bridgman method (HB method) or a temperature gradient method (GF method).

[0002]

2. Description of the Related Art Conventionally, in growing a compound semiconductor single crystal by the boat method, the growth direction of the single crystal is set in the <111> direction parallel to the longitudinal direction of the boat so that the wafer surface of the crystal becomes the (100) plane. , Crystal longitudinal direction (growth direction)
The wafer was cut out obliquely at a predetermined angle.
Further, from the viewpoint of productivity, a method of growing in the <100> direction is partially performed so that the wafer can be cut out perpendicularly to the crystal growth direction. However, the growth in the <100> direction is
Twin defects, which are crystal defects, are more likely to occur than in the 111> direction growth, and the yield is reduced.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an apparatus for producing an AB type compound semiconductor single crystal having a zinc blende type crystal structure by a boat method. , One direction equivalent to the <100> direction of the AB type compound semiconductor single crystal is provided on the crystal growth surface side of the seed crystal, and one direction equivalent to the <100> direction is the seed crystal installation of the boat. And a AB having a zincblende type crystal structure, and a device for manufacturing a compound semiconductor single crystal, which is inclined from the bottom toward the bottom and is inclined 5 to 30 degrees with respect to the horizontal direction of the boat. In the method for producing a type compound semiconductor single crystal by the boat method, one direction equivalent to the <100> direction of the AB type compound semiconductor single crystal is provided on the crystal growth surface side of the seed crystal, and the <100> One direction, which is equivalent to the direction, is that the crystal is grown in a direction from the seed crystal installation portion of the boat toward the bottom direction and inclined at 5 ° to 30 ° with respect to the horizontal direction of the boat. A method for producing a compound semiconductor single crystal is provided.

An embodiment of the present invention will be described below.
Here, an example in which a GaAs single crystal is grown will be described as one example. FIG. 1 shows the orientation of the seed crystal with respect to the crystal growing boat. In the figure, 1 is a seed crystal and 2 is a boat. One direction A equivalent to the <100> direction of the seed crystal
Is provided on the crystal growth surface side of the seed crystal, and the seed crystal is prepared and installed so as to be inclined at an angle θ downward with respect to the longitudinal direction (horizontal direction) B of the boat.

As shown in FIG. 3, when viewed from the crystal growth direction, A
It is a twinning defect to select one adjacent (111) equivalent plane 4, 5 above the (100) equivalent plane 3 to the (100) equivalent plane 3 perpendicular to the <100> equivalent direction which is the direction axis. It is preferable because the occurrence of

Further, as shown in FIG. 2, among the (111) equivalent planes, in the case of a 3-5 group compound semiconductor, a (111) As equivalent plane 4A which is a group 5 element plane and in the case of a 2-6 group compound semiconductor. It is desirable to select the group 6 element face upward because it can further suppress the generation of twin defects.

The AB type compound semiconductor single crystal having a zinc blende type crystal structure according to the present invention includes GaAs and I.
Group 3-5 compound semiconductor single crystal such as nP, 2 such as ZnSe
A Group-6 compound semiconductor single crystal is used.

[0009]

In the present invention, it has been confirmed experimentally that twin defects are reduced by selecting the seed crystal orientation as described above, but its action mechanism is not always clear.

Experimentally, as shown in FIG.
1) The (111) As equivalent surface 4A which is the equivalent surface is converted into (10
0) As compared with the case where it is above the equivalent plane 3, the equivalent plane 5 of the group 3 element such as the (111) Ga equivalent plane is set to (10
0) About 2 times the number of twins was observed when it was above the equivalent plane 3. In addition, when the seed crystal was installed in the orientation shown in FIG. 4, the number of times twinning was generated was about 5 times. From these, it was found that it is more preferable to place one (111) As equivalent surface 4A, which is one (111) equivalent surface, above the (100) equivalent surface 3 as shown in FIG.

These results are crystallographically <100.
Azimuth equivalent to the> direction, that is, <010>, <001
It is conceivable that the same result can be obtained even if the operation is performed in the>, <-100>, <0-10>, and <00-1> directions (-indicates the opposite direction).

Further, the boat shape is such that the cross-sectional shape perpendicular to the longitudinal direction is an ellipse of more than half, and the flatness of the ellipse is such that the obtained crystal has a cross-sectional shape in the (100) plane direction close to a circle. When a (100) circular wafer is cut out from a single crystal by using the boat described above, a shape close to the circular wafer can be obtained by slicing,
The loss due to cutting can be reduced.

[0013]

EXAMPLES Examples for producing a GaAs single crystal will be described below.

FIG. 1 shows the orientation of the seed crystal 1 with respect to the boat 2 for growing a crystal. FIG. 2 shows the (100) equivalent plane 3 seen from the crystal growth direction of the seed crystal 1 and the (111) equivalent plane 3 adjacent to it.
The relationship between equivalent planes is shown. FIG. 5 shows a cross-sectional view in the longitudinal direction of the reaction vessel when the boat 2 is used for growth. FIG. 6 shows a cross-sectional view of a boat for growing crystals which has a semicircular cross section perpendicular to the longitudinal direction. FIG. 7 shows a cross-sectional view of the boat for crystal growth which has a sectional shape perpendicular to the longitudinal direction, in which 80% is elliptical and the remaining upper portion is open.

In the figure, 1 is a seed crystal, 2 is a boat, 3 is a (100) equivalent plane, 4A is a (111) As equivalent plane, and 5A.
Is a (111) Ga equivalent surface, 6 is Ga, 7 is a reaction vessel, 8
Indicates As.

Example 1 A GaAs seed crystal 1 is placed at a predetermined position on a boat 2 as shown in FIG. 1 using a boat having a semicircular cross section perpendicular to the longitudinal direction of the boat for growing crystals shown in FIG. Then, the angle between the <100> direction A of the seed crystal 1 and the boat longitudinal direction (horizontal direction) B is inclined downward by θ = 10 °. At this time, as shown in FIG. 2, one of the (111) As equivalent planes 4A adjacent to the (100) equivalent plane 3 perpendicular to the A direction as viewed from the crystal growth direction of the seed crystal 1 is (100).
It is arranged above the equivalent plane 3.

As shown in FIG. 5, 21 Ga 6 is placed in the boat 2.
00g is put and 2300g of As8 is added to the other end of the reaction vessel 7.
The inside of the reaction vessel 7 is depressurized to a vacuum state and sealed. Next, the reaction vessel 7 is placed in a crystal growth furnace, and As in the reaction vessel 7 is changed to 6
It is heated to 00 ° C and the As vapor pressure in the reaction vessel 7 is set to 1 atm.
Maintain the boat inside the reaction vessel 7 at 1200 ° C.
GaAs is synthesized by reacting a and As vapor.

Thereafter, the temperature is further raised to set the seed crystal temperature to 123.
At 8 ° C., the temperature gradient in the GaAs melt is set to about 0.5 ° C./cm, and the seed crystal and the GaAs melt are brought into contact with each other. Then, the temperature of the melt is gradually lowered and cooled to grow crystals. Crystals can be easily observed from above the boat during crystal growth.
After completely solidifying, the temperature was further lowered to room temperature and the crystals were taken out to obtain 4150 g of GaAs single crystal.

When the orientation of the seed crystal was set to θ = 0 ° in the <100> direction, twin defects frequently occurred were hardly generated, and the crystal could be stably obtained.

(Embodiment 2) As shown in FIG. 7, a GaAs seed crystal 1 is used as shown in FIG. 1 by using a boat for growing crystals which has an elliptical cross section perpendicular to the longitudinal direction of 80%. At a predetermined position on the boat 2 and the <100> of the seed crystal 1.
The angle between the direction A and the boat longitudinal direction (horizontal direction) B is inclined downward by θ = 10 °. At this time, as seen from the crystal growth direction of the seed crystal as shown in FIG.
One of the (111) As equivalent planes 4A adjacent to the (00) equivalent plane 3 is located above the (100) equivalent plane 3.

As shown in FIG. 5, 21 Ga 6 is placed in the boat 2.
00g is put and 2300g of As8 is added to the other end of the reaction vessel 7.
The inside of the reaction vessel 7 is depressurized to a vacuum state and sealed. Next, the reaction vessel 7 was placed in a crystal growth furnace, and crystal growth was carried out in the same manner as in Example 1 to obtain 4150 g of a GaAs single crystal.

When the orientation of the seed crystal was set to θ = 0 ° in the <100> direction, twin defects frequently occurred were hardly generated, and the crystal could be stably obtained.

When a (100) plane circular wafer is prepared from the obtained crystal, the cross section of the obtained crystal in the (100) plane direction can be made into a shape close to a circle. When obtaining a (100) circular wafer from a single crystal based on the boat shape, the shape close to the circular wafer can be obtained by slicing. Therefore, it is possible to reduce the loss due to cutting.

As an example of the compound semiconductor single crystal, an experiment for growing a GaAs single crystal was tried by changing various values of θ. As shown in FIG. 2, the (111) As equivalent surface 4A is converted into (10
0) Above the equivalent plane 3. The θ is -30 to 30
Up to 8 degrees were changed in 8 ways, and the growing experiment was performed once each. In this experiment, when twins were observed during growth, meltback was performed, growth was performed several times until twin defects disappeared, and the number of observed twin defects was examined.

The number of twinning occurrences observed during the growth in each experiment is summarized in Table 1. As can be seen from Table 1, θ
It can be seen that the frequency of twinning is relatively large from -30 ° to 0 °, but the frequency of twinning decreases from 5 ° to 30 °.

[0026]

[Table 1]

[0027]

As described above, the present invention has the following excellent effects.

(1) As compared with the case where the seed crystal orientation is grown to <100>, the occurrence frequency of twin defects is reduced and the yield and throughput are improved.

(2) When the (100) wafer is cut out from the crystal, the cutting can be performed in a direction close to the direction perpendicular to the longitudinal direction of the crystal, as compared with the case where the seed crystal orientation is <111>. Therefore, processing loss can be reduced, and the number of wafers that can be cut out from one crystal increases.

(3) If the cross-sectional shape perpendicular to the longitudinal direction of the boat is elliptical more than half, the flatness of the ellipse is such that the crystal obtained has a cross-sectional shape in the (100) plane direction close to a circle. Can be set to Therefore, (10
In the case of obtaining a circular wafer of 0) plane, the crystal is sliced to obtain a shape close to the circular wafer as it is, so that the loss due to cutting can be reduced.

(4) Product cost can be reduced by improving economy and workability.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the orientation of a seed crystal with respect to a crystal growing boat.

FIG. 2 is a front view showing the relationship between a (100) equivalent plane viewed from the crystal growth direction of a seed crystal and a (111) As equivalent plane adjacent thereto.

FIG. 3 is a front view showing a relationship between a (100) equivalent plane viewed from a crystal growth direction of a seed crystal and a (111) equivalent plane adjacent thereto.

FIG. 4 shows a relationship between a (100) equivalent plane viewed from the crystal growth direction of a seed crystal and a (111) equivalent plane adjacent thereto,
The front view at the time of there being another (100) equivalent surface in the upper part of a (100) equivalent surface.

FIG. 5 is a cross-sectional view in the longitudinal direction of a reaction container in the case of growing using a boat.

FIG. 6 is a cross-sectional view of a boat having a semicircular cross-sectional shape perpendicular to the longitudinal direction.

FIG. 7 is a cross-sectional view of a boat whose cross-sectional shape perpendicular to the longitudinal direction has an elliptical shape of 80% of the circumference.

[Explanation of symbols]

 1 seed crystal 2 boat 3 (100) equivalent surface 4 5 group 5 element equivalent surface 5 3 group element equivalent surface 4A (111) As equivalent surface 5A (111) Ga equivalent surface 6 Ga 7 reaction vessel 8 As

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[Procedure amendment]

[Submission date] April 16, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Description of Reference Signs] 1 seed crystal 2 boat 3 (100) equivalent surface 4 equivalent surface of group 5 element 5 equivalent surface of group 3 element 4A (111) As equivalent surface 5A (111) Ga equivalent surface 6 Ga 7 reaction vessel 8 As

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Sato 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (6)

[Claims] 1. An apparatus for producing an AB type compound semiconductor single crystal having a zinc blende type crystal structure by a boat method, wherein one direction equivalent to the <100> direction of the AB type compound semiconductor single crystal is a seed crystal. Is provided on the crystal growth surface side of the boat, and one direction equivalent to the <100> direction is from the seed crystal installation portion of the boat toward the bottom direction and is inclined 5 ° to 30 ° with respect to the horizontal direction of the boat. An apparatus for producing a compound semiconductor single crystal, which is characterized in that 2. A method of manufacturing an AB type compound semiconductor single crystal having a zinc blende type crystal structure by a boat method, wherein one direction equivalent to the <100> direction of the AB type compound semiconductor single crystal is a seed crystal. Is provided on the crystal growth surface side of the boat, and one direction equivalent to the <100> direction is from the seed crystal installation portion of the boat toward the bottom direction and is inclined 5 ° to 30 ° with respect to the horizontal direction of the boat. A method for producing a compound semiconductor single crystal, which comprises growing a crystal in a vertical direction. 3. The seed crystal <1 as viewed from the crystal growth direction.
One (111) equivalent plane adjacent to the (100) equivalent plane perpendicular to one direction equivalent to the 00> direction is
0) The method for producing a compound semiconductor single crystal according to claim 2, which is selected above the equivalent plane. 4. A group 5 element plane in the case of a 3-5 group compound semiconductor and a group 6 element plane in the case of a 2-6 group compound semiconductor are selected upward from the (111) equivalent planes. Method for producing compound semiconductor single crystal. 5. The boat has a cross-sectional shape perpendicular to the longitudinal direction of more than half an elliptic arc, and the flatness of the ellipse is such that the crystal obtained has a cross-sectional shape in the (100) plane direction close to a circle. 3. The method for producing a compound semiconductor single crystal according to claim 2. 6. The method for producing a compound semiconductor single crystal according to claim 2, wherein the AB type compound semiconductor having a zinc blende type crystal structure is a GaAs single crystal.