JPH0710680A - Production of single crystal of compound semiconductor - Google Patents

Abstract

PURPOSE:To increase the yield of single crystal with lineage defect inhibited, when the single crystal of compound semiconductor is allowed to grow in the direction of <100> by the boat method. CONSTITUTION:The one direction equivalent to the <110> direction orthogonal to one direction equivalent to the <100> direction parallel with the longitudinal direction of the boat for the crystal to be grown is set to almost perpendicular so that three kinds of unparallel (111) facet 1a, 1b, and 1c is developed on the crystalline free surface and allowed to grow.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in growing a compound semiconductor single crystal such as GaAs by the boat method, the growth direction of the single crystal is generally in the <111> direction parallel to the longitudinal direction of the boat.
The wafer was cut out at a predetermined angle with respect to the longitudinal direction (growth direction) of the crystal so that the wafer surface of the crystal became the (100) plane. 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. Reported examples include JP-A-1-139223 and JP-A-2-11165.
And Japanese Patent Application No. 3-195846 and Japanese Patent Application No. 4-82792 by the present applicant.

For these methods, <111> direction growth and <100> direction growth are compared. When the crystal growth direction that is generally performed conventionally is set to the direction equivalent to the <111> direction, in order to cut out a (100) wafer obliquely with respect to the crystal longitudinal direction, for example, to cut out a wafer of 50 mmφ, The required crystal height of 35 mm was sufficient. On the other hand, when the crystal growth direction is made equal to the <100> direction as in the present invention, the same 5
The crystal height for cutting out a 0 mmφ wafer must be at least 50 mm. As described above, in the <100> direction growth, it is necessary to increase the height of the crystal.

Further, the cross-sectional shape of the boat perpendicular to the longitudinal direction is generally a semicircular shape or a U-shape which is used in the <111> direction growth. In <100> direction growth, it is necessary to use a boat having a shape close to a circle in order to efficiently cut a circular (100) wafer, and the width near the center of the crystal is made larger than the width at the top of the crystal. Furthermore, it is necessary to reduce the width at the bottom of the crystal.

As the seed crystal orientation, a <110> equivalent direction, which is substantially parallel to the longitudinal direction of the boat and perpendicular to the <100> direction, coincides with one of the normal directions of the free surface which does not directly contact the boat on the crystal surface. There is a method of making it.

However, the growth in the <100> direction is <11
Lineage defects, which are crystal defects, are much more likely to occur than in 1> direction growth. In particular, many lineage defects are generated from above the crystal, resulting in a decrease in yield.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to prevent the occurrence of lineage defects in <100> direction growth and decrease the yield. It is a solution.

[0008]

The present invention has been made to solve the above-mentioned problems, and as a first invention, the production of a compound semiconductor single crystal having a zinc blende type crystal structure by the boat method. In the method, one angle equivalent to the <100> direction of the compound semiconductor single crystal forms an angle within 30 degrees with the boat longitudinal direction, and one direction equivalent to the <110> direction perpendicular to the <100> direction. Is selected to be substantially vertical, and an equivalent crystal habit appears on the (111) plane that is substantially perpendicular to the longitudinal direction of the boat on at least a part of the free surface of the straight body of the crystal to be grown. The present invention provides a method for producing a compound semiconductor single crystal characterized by the above.

As a preferred embodiment of the first invention,
It is characterized in that at least a part of the free surface of the straight body of the crystal to be grown, three or more kinds of (111) planes that are not parallel have an equivalent crystal habit.

As a second invention, in a method of manufacturing a compound semiconductor single crystal having a zinc blende type crystal structure by a boat method, one direction equivalent to the <100> direction of the compound semiconductor single crystal is the boat longitudinal direction. The angle formed by the crystal growth interfaces on both sides in contact with the boat is 60 degrees or more from the seed crystal side in a crystal horizontal cross section within at least 10 mm in the depth direction from the free surface of the crystal to be grown. The present invention provides a method for producing a compound semiconductor single crystal characterized by:

As a preferred embodiment of the second invention, in the furnace core tube near the crystal growth interface of the growing furnace for growing the compound semiconductor single crystal, the temperature distribution in the radial direction in the horizontal plane is such that the temperature at the central portion is low and It is characterized in that the temperature of the part is increased to give a temperature gradient of 1.1 ° C./cm or more and 5 ° C./cm or less from the central part toward the peripheral part.

Further, as the preferred orientation of the seed crystal in the first and second inventions, when viewed from the crystal growth direction,
Of the four (111) equivalent planes adjacent to the (100) equivalent plane perpendicular to the <100> direction of the seed crystal, if the crystal to be grown is a Group 3-5 compound semiconductor, a Group 5 element plane, 2-
In the case of a Group 6 compound semiconductor, the Group 6 element plane is selected upward.

Further, the (111) equivalent plane facet which appears on the upper part of the crystal and is substantially perpendicular to the longitudinal direction of the boat preferably has a length of 1/4 or more of the crystal free surface width in the direction perpendicular to the longitudinal direction of the crystal. It is also preferable to generate it near the center of the free surface width. Further, it is preferable to generate as many portions as possible in the longitudinal direction of the crystal straight body portion, and further it is effective for suppressing lineage defects by generating the crystal over the entire crystal.

Further, by simultaneously generating at least one of two kinds of non-parallel facets on both sides of the (111) equivalent facet which appears almost perpendicular to the longitudinal direction of the boat, it is possible to stabilize the growth interface shape. preferable.

Furthermore, it is preferable that most of the solid-liquid interface of the free surface in the width direction is constituted by the three types of (111) equivalent facets which are not parallel. Further, it is more preferable that the portion where three kinds of (111) equivalent facets that are not parallel are generated is long in the crystal longitudinal direction because the lineage suppression effect is large.

1 (a) and 1 (b) schematically show examples of the growth interface shape when observing the free surface during crystal growth according to the present invention. It can be seen from FIG. 1A that most of the growth interface shape is composed of facets 1a, 1b, and 1c equivalent to three types of (111) planes that are not parallel. In addition, FIG. 1B shows the growth interface shape when a (111) facet 1a perpendicular to the boat longitudinal direction, which occupies more than half of the growth interface width, appears near the center in the growth interface width direction.

In the shape of the growth interface in the horizontal section below the free surface, the angle θ between the boat and the crystal growth interfaces on both sides in contact with the boat is the seed crystal in the crystal horizontal section within at least 10 mm in the depth direction. It must be 60 degrees or more as viewed from the side, and more preferably 90 degrees or more. Further, the shape of the growth interface is preferably convex as a whole from the seed crystal side to the melt side, and more preferably has no local depression.

In particular, in the portion where the crystal width increases from the upper part of the crystal to the central part in the cross section perpendicular to the longitudinal direction of the crystal, the normal direction of the crystal surface has a heat radiation effect attached to the upper part of the crystal growing furnace. Facing the crystal observation window. Therefore, it is considered that the heat radiation from the surface of the upper part of the crystal becomes large. Therefore, the growth interface shape in this vicinity is likely to be concave with respect to the melt in the vicinity of contact with the boat, and lineage defects are likely to occur. For this reason, the upper part of the cross-sectional shape perpendicular to the crystal longitudinal direction, which has the largest width, that is,
In the part where the normal direction of the crystal surface is above the horizontal direction, the horizontal growth interface shape of the crystal is defined as (θ
Is 60 ° or more), which is effective and more important for suppressing lineage defects. Further, it is more preferable that the shape of the growth interface in the horizontal direction is completely convex over the entire crystal.

FIGS. 2A and 2B show the growth interface shape of a crystal horizontal cross section of 10 mm in the depth direction from the free surface during crystal growth according to the present invention. FIG. 2A shows an example (W-type growth interface 2) when the angle θ between the boat and the growth interface is 60 degrees or more and 90 degrees or less. In addition, in FIG.
An example (convex growth interface 3) when θ is 90 degrees or more is shown. It can be seen that this crystal growth interface shape is convex from the seed crystal side to the melt side, and there is no locally concave portion. This growth interface shape can be observed by cutting and etching a predetermined position of the grown crystal.

Further, in the furnace core tube near the crystal observation window of the crystal growth furnace, the temperature distribution in the radial direction in the horizontal plane is such that the temperature at the central portion is low, the temperature at the peripheral portion is high, and the temperature goes from the central portion to the peripheral portion. By providing a temperature gradient of 1.1 ° C./cm or more and 5 ° C./cm or less, the angle θ between the boat and the solid-liquid interface can be set to 60 degrees or more. Moreover, the appearance of facets (particularly the facets having the shape shown in FIG. 1A) is also effective, and it is effective in suppressing lineage defects.

FIG. 3 shows the temperature measurement positions in the cross section of the furnace core tube 4 near the crystal observation window of the crystal growth furnace. In FIG. 3, point a is substantially the center of the furnace core tube, and points b ₁ and b ₂ are points separated from point a by a distance corresponding to the radius r (cm) of the crystal to be grown. Here, Ta, Tb ₁ and Tb ₂ are temperatures at points a, b ₁ and b ₂ , respectively. Ta <Tb
₁ and Ta <Tb ₂ , and 1 <(Tb ₁
-Ta) / r <With _{5,1 <(Tb 2 -Ta) /} r <5 it is possible to obtain the temperature distribution as described above. In _{addition, -0.3 <(Tb 1 -Tb 2} ) / 2r <
By setting it to 0.3, the symmetry of the crystal growth interface is improved, which is more preferable.

Further, proper selection of the temperature distribution in the axial direction of the growth furnace and the temperature gradient in the vertical direction near the crystal growth interface in the crystal growth furnace, and the temperature of the raw material melt has a great effect on the appearance of facets. I understood it.

As the orientation of the seed crystal, an angle equivalent to the <100> direction and the longitudinal direction of the boat is set within 30 degrees, preferably within 30 degrees in the vertical direction, so that the solid-liquid interface can be controlled. It is preferable that the facet generation becomes symmetric. Further, by making the <100> direction parallel to the longitudinal direction of the boat, it is easy to cut out a (100) equivalent plane wafer, which is preferable.

The projection vector of the <110> equivalent direction vector perpendicular to the <100> equivalent direction of the seed crystal orientation on the cross section perpendicular to the boat longitudinal direction is in direct contact with the boat on the surface of the crystal to be grown. By making it coincide with one of the normal directions to the non-surface (free surface), facets on the free surface are likely to occur, which is preferable. Furthermore, by making the <110> direction point vertically upward, the facet shape tends to be symmetrical,
Moreover, it is more preferable because three types of facets that are not parallel are likely to occur.

Also, taking the case of a GaAs crystal of the Group 3-5 crystal as an example, the pit shape generated when a wafer cut out perpendicularly to the <100> direction of the seed crystal is etched by molten KOH The seed crystal orientation is preferably such that the seed-side surface of the wafer has a horizontally long shape (FIG. 4A) and the tail-side surface has a vertically long shape (FIG. 4B).
That is, when viewed from the crystal growth direction, the above-mentioned <100 of the seed crystal
> Four (1) adjacent to the (100) equivalent plane perpendicular to the direction
11) Among the equivalent planes, if the crystal to be grown is a group 3-5 compound semiconductor, the group 5 element plane is selected upward, and if it is a group 2-6 compound semiconductor, the group 6 element plane is selected upward to form facets. It is preferable because it can appear stably.

As for the cross-sectional shape perpendicular to the longitudinal direction of the boat, the shape in which the width of the bottom is narrow, the width of the center is wide, and the width of the top is narrow again is small in the circularization loss of the sliced wafer. Therefore, it is preferable that it is a circular arc or an elliptical arc.

As the boat material, quartz glass,
PBN, AlN, etc. are suitable.

As the compound semiconductor single crystal having a zinc blende type crystal structure in the present invention, a Group 3-5 compound semiconductor single crystal such as GaAs and InP, and a Group 2-6 compound semiconductor single crystal such as ZnSe are used. .

[0029]

In the present invention, it has been experimentally confirmed that by selecting the crystal growth interface shape and seed crystal orientation as described above, the lineage defect defects are reduced and the crystal yield is improved. The mechanism is not always clear, and the following two causes are presumed.

The first cause is growth in <111> direction and <1>.
This is due to the difference in boat shape that is generally used in the 00> direction growth. This generally means that lineage defects occur
Since the dislocation defects easily propagate perpendicularly to the interface shape, it is said that the dislocation defects are concentrated in the portion of the growth interface that is concave on the crystal side, resulting in a lineage defect. Due to the characteristic boat shape used for <100> direction growth, <111>
This is because the growth interface is more likely to be concave than in directional growth.

As described above, this difference in boat shape is
In the case of <100> direction growth, the height of the crystal needs to be increased as compared with the case where the crystal growth direction that is generally performed conventionally is equivalent to the <111> direction. Further, the cross-sectional shape perpendicular to the longitudinal direction of the boat is generally a semicircular shape or a U-shape which is used in the <111> direction growth, but in the <100> direction growth, the width of the upper part of the crystal is On the other hand, it is necessary to use a boat having a shape close to a circle in which the width near the center of the crystal is increased and the width is decreased at the bottom of the crystal.

In particular, in the part where the crystal width increases from the upper part of the crystal to the central part, the normal direction of the crystal surface is directed to the crystal monitoring window attached to the upper part of the crystal growth furnace and having a heat dissipation effect. . Therefore, it is considered that the heat radiation from the surface of the upper part of the crystal becomes large. Therefore, it is considered that heat radiation from the surface of the upper part of the crystal becomes large, and the shape of the growth interface in this vicinity is likely to be concave with respect to the melt in the vicinity of contact with the boat, and lineage defects are likely to occur.

On the other hand, in a boat such as a semicircular boat or a U-shaped boat which is generally used for <111> direction growth,
Since most of the normal vector of the crystal surface under the free surface faces the lower part of the crystal growth furnace, it will be heated, and the growth interface shape will not be extremely concave with respect to the melt, and lineage defects will not occur. Considered to be few.

The second cause is considered to be a difference in crystallographic growth mechanism due to the fact that the crystal growth orientation is selected to be the <100> equivalent direction.

This is inferred from the results of two experiments.
First, as a result of trying to grow a seed crystal in the <100> direction using a semicircular boat used for <111> growth,
It has been experimentally found that lineage defects are more likely to occur than in the case of <111> direction growth.

Secondly, in the <100> direction growth, the angle θ between the boat wall surface and the growth interface becomes 60 degrees or less in the horizontal cross section when grown in the above-mentioned round boat. From a number of experiments, it was found that lineage defects are likely to occur very critically and that the occurrence of lineage defects can be suppressed by setting θ to 60 degrees or more.

As one of the causes that lineage defects are easily generated when θ is 60 degrees or less, in <100> direction growth,
The (211) equivalent plane, which has a relatively low index plane in the lateral direction of the boat and has a characteristic atomic arrangement, is θ = about 55 degrees. For unknown reasons, lineage is generated when the growth interface approaches this (211) plane. It is easy to do.

From the above, the control of the crystal growth interface shape near the free surface becomes particularly important in the <100> direction growth, and by devising the seed crystal orientation and the temperature distribution in the growth furnace, the straight body part I found that facets appeared on the free surface.

This means that the interface shape of the free surface becomes parallel to the isotherm determined from the heat balance of the melt and the crystal when facets are not made to appear. However, this isotherm becomes concave with respect to the melt near the boat due to heat radiation from the surface of the crystal upper part due to the boat shape as described above.

However, under the growth conditions in which the facets appear on the free surface, the melt is in a supercooled state near the facets, and the growth interface shape is not parallel to the isotherm.
By generating (111) equivalent facets perpendicular to the boat longitudinal direction near the center of the free surface, the growth interface shape near the center is not parallel to the isotherm. As a result, the growth interface appearing around the facet is also affected by this facet, is not necessarily parallel to the isotherm, and tends to have no recess for the melt near the boat.

From the above, the (111) equivalent facet appearing on the free surface, which is perpendicular to the longitudinal direction of the boat, is effective in suppressing lineage when it is long in the width direction, and it may be 1/4 or more of the free surface width. preferable.

Further, as a method of stably controlling the growth interface shape on the upper part of the crystal, as shown in FIG. 1 (a), the equivalent facets appear on the three types of (111) planes which are not parallel to each other. As a result, the shape of the interface on the free surface is not parallel to the isotherm, and can be stably convex to the melt. The growth interface shape under the free surface is also influenced by the growth interface shape on the free surface and can be made to be stable and completely convex to the melt as shown in FIG.

Even in the <111> direction growth, facets as shown in FIG. 1B may appear at first glance when observed from the free surface, but naturally the growth direction is different. For crystallographic reasons, the angle of this facet is significantly different in the vertical cross section in the longitudinal direction of the boat, and the examples mentioned about the facets generated on the straight body free surface by <100> direction growth in the boat method are as follows. Absent. In particular, facets like Fig. 1 (a)
111> direction growth does not occur, <100>
It was found that the crystallographic properties peculiar to the direction cause the generation, and the method for generating such a facet was found.

Even in the <100> direction growth, facet generation in the boat neck portion (portion close to the seed crystal) having a small crystal diameter is relatively easy regardless of the growing conditions.
In the 100> direction growth, in order to stably generate facets in a portion having a large crystal diameter such as the straight body portion of the boat, it is necessary to devise the crystal orientation and the temperature distribution of the growth furnace. As a method for this, the following method has been experimentally found to be excellent.

First, as the orientation of the seed crystal, one angle equivalent to the <100> direction makes an angle of 30 with the longitudinal direction of the boat.
By setting the angle within the range of 30 degrees and the angle within the range of 30 degrees in the vertical direction, the facet generation at the solid-liquid interface tends to be symmetrical, which is preferable.

Further, the <100> equivalent direction of the seed crystal which is nearly parallel to the boat longitudinal direction, and the projection vector of the perpendicular <110> equivalent direction vector to the cross section perpendicular to the boat longitudinal direction of the crystal surface to be grown. Of these, it is preferable that the (111) facet appears in almost the left-right symmetry with the longitudinal direction of the boat by making it coincide with one of the normal directions to the free surface that does not come into direct contact with the boat. Furthermore, it is more preferable that the <110> direction is directed vertically upward because the facet shape is likely to be bilaterally symmetric and three types of non-parallel facets are likely to occur.

In the case of a GaAs crystal of Group 3-5 crystal, the pit shape generated when a wafer cut out perpendicularly to the <100> direction of the seed crystal is etched by molten KOH is as follows. The seed crystal orientation is preferably such that the surface on the seed side of the wafer has an oblong shape (FIG. 4A) and the surface on the tail side has an oblong shape (FIG. 4B).

That is, of the four (111) equivalent planes adjacent to the (100) equivalent plane perpendicular to the <100> direction of the seed crystal as seen from the crystal growth direction, three crystals should be grown.
In the case of a Group 5 compound semiconductor single crystal, a Group 5 element plane,
In the case of a Group 6 compound semiconductor single crystal, it was experimentally confirmed that facets can be stably appeared by selecting the Group 6 element plane upward.

Further, the temperature conditions in the growth furnace have been described above, and the details thereof will be omitted. However, the temperatures of the inner cross section of the furnace core tube near the crystal observation window of the crystal growth furnace are set to Ta <Tb ₁ and Ta <Tb _2, and 1 <(Tb ₁ −Ta) / r <5, 1 <(Tb ₂ −T
It is preferable that a) / r <5 because the growth interface is projected to the melt. Furthermore, it is preferable to optimize the temperature gradient in the growth furnace axial direction near the crystal solid-liquid interface, the vertical temperature gradient, and the temperature of the melt in order to make facets appear in <100> direction growth.

[0050]

EXAMPLE An example of manufacturing a GaAs compound semiconductor single crystal will be described below.

Example 1 A boat for growing a crystal having a cross-section perpendicular to the longitudinal direction of the boat having a circular shape of about 80% was used and the crystal to be grown was parallel to the longitudinal direction of the boat <10.
The seed crystal was set so that one direction equivalent to the <110> direction, which is orthogonal to one direction equivalent to the 0> direction, is substantially vertical.

As shown in FIG. 5, 2100 g of Ga (reference numeral 6) was placed in the boat 5, 2300 g of As (reference numeral 8) was placed at the other end of the reaction vessel 9, and the inside of the reaction vessel 9 was evacuated and sealed. Wear. Next, the reaction vessel 9 is put into a crystal growth furnace, As in the reaction vessel 9 is heated to 600 ° C., the vapor pressure of As in the reaction vessel 9 is maintained at 1 atm, and the boat in the reaction vessel 9 is further heated. , Ga and As vapor react to synthesize GaAs. Then, the seed crystal 7 and the GaAs melt are brought into contact with each other. After that, the temperature of the melt is gradually lowered and cooled to grow crystals.

The temperatures of the inner cross section of the furnace core tube (FIG. 3) near the crystal observation window of the crystal growth furnace are Ta <Tb ₁ and Ta <Tb ₂ ,
(Tb ₁ −Ta) / r = 2, (Tb ₂ −Ta) / r =
It was set to 2. At this time, a facet as shown in FIG. 1B was made to appear as the growth interface shape of the free surface. After being completely solidified, the temperature was further lowered to room temperature and the crystal was taken out to obtain 4150 g of a GaAs single crystal.

The obtained crystals were of good quality without lineage defects. When the growth interface shape of a horizontal section of 10 mm below the free surface of this crystal is observed by etching, the angle θ formed by the growth interface and the boat is about 70 as shown in FIG.
It was degree.

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 formed 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.

(Embodiment 2) A boat having a cross-section perpendicular to the longitudinal direction of a crystal-growing boat of approximately 80% circular was used, and the crystal to be grown was parallel to the boat longitudinal direction <10.
One direction equivalent to the <110> direction, which is orthogonal to the one direction equivalent to the 0> direction, is substantially vertical and is perpendicular to the <100> direction of the seed crystal when viewed from the crystal growth direction. Four (11) adjacent to the (100) equivalent plane
1) Of the equivalent planes, the seed crystal was set so that the crystal to be grown had the As element plane selected upward.

As in Example 1, the reaction vessel 9 was placed in a crystal growth furnace, As in the reaction vessel 9 was heated to 600 ° C., and the vapor pressure of As in the reaction vessel 9 was maintained at 1 atm. The boat in the reaction vessel 9 is further heated to react Ga and As vapor to synthesize GaAs. Then, the seed crystal and the GaAs melt are brought into contact with each other. After that, gradually lower the temperature of the melt,
Cool and grow crystals.

The temperatures of the inner cross section of the furnace core tube (FIG. 3) near the crystal observation window of the crystal growth furnace are Ta <Tb ₁ and Ta <Tb ₂ ,
(Tb ₁ −Ta) /r=2.5, (Tb ₂ −Ta) / r
= 2.5. At this time, at the solid-liquid interface of the free surface,
Equivalent crystal habits (facets) were made to appear on three types of (111) planes that are not parallel as in (a). After completely solidifying, the temperature is further lowered to room temperature and the crystals are taken out to obtain Ga.
It was possible to obtain 4150 g of As single crystal.

The obtained crystals were of good quality without lineage defects. When the growth interface shape of a horizontal section of 10 mm below the free surface of this crystal is observed by etching, the angle between the growth interface and the boat is about 14 as shown in FIG.
It was 0 degree and was completely convex on the melt side.

From the obtained crystal, a (100) plane circular wafer could be efficiently prepared in the same manner as in Example 1.

[0061]

As described above, the present invention has the following excellent effects. (1) When the seed crystal orientation is grown to <100>, facets appear on the free surface by optimizing the seed crystal orientation and the temperature environment in the growth furnace, and lineage hardly occurs in the growth interface shape. By doing so, the yield is improved.

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

[Brief description of drawings]

FIG. 1 is a plan view of a growth interface shape of a free surface during crystal growth according to the present invention, in which (a) is three types of non-parallel (11).
1) An example in which an equivalent facet appears in the plane, and (b) is an example in which an equivalent facet appears in the (111) plane perpendicular to the boat longitudinal direction.

FIG. 2 is a plan view of a growth interface shape in a crystal horizontal cross section of 10 mm in a depth direction from a free surface during crystal growth according to the present invention, in which (a) is an angle θ formed between a boat wall surface and the growth interface.
Is 60 degrees or more and 90 degrees or less. In (b), θ is 90
It is an example in which it is completely convex on the melt side at a temperature of more than 100 degrees.

FIG. 3 is a cross-sectional view perpendicular to the longitudinal direction inside the furnace core tube near the crystal observation window.

FIG. 4 is an explanatory view showing a pit shape when a wafer cut out from a GaAs crystal grown by the present invention is etched with molten KOH, and (a) is a pit shape of a seed side surface of the wafer, (B) is a pit shape on the tail side surface of the wafer.

FIG. 5 is a cross-sectional view in the longitudinal direction of a reaction container when a crystal is grown by a boat method, showing an embodiment of the present invention.

[Explanation of symbols]

1a to 1c: Crystal habits (facets) equivalent to three types of (111) that are not parallel 2: W-type growth interface 3: Convex-type growth interface 4: Furnace core tube 5: Boat 6: Ga 7: Seed crystal 8 : As 9: Reaction vessel

Claims (5)

[Claims] 1. A method for producing a compound semiconductor single crystal having a zinc blende type crystal structure by a boat method, wherein an angle formed by one direction equivalent to the <100> direction of the compound semiconductor single crystal is the boat longitudinal direction. Within 30 degrees, <1
The seed crystal orientation is selected such that one direction equivalent to the <110> direction, which is perpendicular to the <00> direction, is a substantially vertical direction, and the boat longitudinal direction is at least part of the free surface of the crystal straight body part to be grown. A method for producing a compound semiconductor single crystal, characterized in that a crystal habit equivalent to a (111) plane substantially perpendicular to is appeared. 2. The production of a compound semiconductor single crystal according to claim 1, wherein three or more (111) planes which are not parallel have crystal habits which are equivalent to each other on at least a part of the free surface of the crystal body to be grown. Method. 3. A method for producing a compound semiconductor single crystal having a zinc blende type crystal structure by a boat method, wherein an angle formed by one direction equivalent to the <100> direction of the compound semiconductor single crystal is the boat longitudinal direction. Within 30 degrees, and in the crystal horizontal cross section within at least 10 mm in the depth direction from the free surface of the crystal to be grown, the angle formed by the crystal growth interfaces on both sides in contact with the boat should be 60 degrees or more from the seed crystal side. A method for producing a compound semiconductor single crystal characterized. 4. A temperature distribution in a radial direction in a horizontal plane in a furnace core tube in the vicinity of a crystal growth interface of a growth furnace where a compound semiconductor single crystal is to be grown has a lower temperature in a central portion and a higher temperature in a peripheral portion, 1.1 ℃ / c from the center to the periphery
The method for producing a compound semiconductor single crystal according to claim 1, wherein a temperature gradient of m or more and 5 ° C./cm or less is applied. 5. The seed crystal <1 as viewed from the crystal growth direction.
Of the four (111) equivalent planes adjacent to the (100) equivalent plane perpendicular to the 00> direction, if the crystal to be grown is a Group 3-5 compound semiconductor, a Group 5 element plane, a Group 2-6 compound The method for producing a compound semiconductor single crystal according to claim 1, wherein in the case of a semiconductor, the group 6 element plane is selected upward.