JP2011195388A - Group iii nitride semiconductor crystal, method for producing the same, and ground substrate for growing group iii nitride semiconductor crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a group III nitride semiconductor crystal having a large area and a low dislocation density with a simple process.SOLUTION: A first crystal growth face (1) having a width of ≥100 μm and a second crystal growth face (2) having a width of ≥100 μm are arranged in such a manner that the first crystal growth face (1) and the second crystal growth face (2) are crossed at an angle of ≥10° and <180°, and a group III nitride semiconductor crystal is grown under such a crystal growth face arrangement condition that the crystal having a cross sectional area of ≥40 mmis grown by only crystal growth from the first crystal growth face (1) and the second crystal growth face (2).

Description

  The present invention relates to a method for producing a group III nitride semiconductor crystal such as gallium nitride. In particular, the present invention relates to a method capable of growing a high-quality group III nitride semiconductor crystal without taking over defects such as dislocations existing in the substrate. The present invention also relates to a group III nitride semiconductor crystal produced by the method and a substrate used in the method.

  Group III nitride semiconductors typified by gallium nitride have a large band gap, and because the interband transition is a direct transition type, they are relatively short, such as light emitting diodes such as ultraviolet, blue and green, and semiconductor lasers. It is a promising material as a substrate for semiconductor devices such as light emitting elements on the wavelength side and electronic devices.

  Nitride semiconductors include hydride vapor phase epitaxy (HVPE), ammonothermal, organometallic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and liquid phase epitaxy (LPE). ), A sublimation method or the like. Among these, the HVPE method has attracted attention because of its relatively high growth rate, and the HVPE method and ammonothermal method have attracted attention because they are relatively suitable for bulk growth. For example, when using a vapor phase growth method such as the HVPE method or the MOCVD method, a group III nitride semiconductor crystal can be grown on the surface of the base substrate by supplying the source gas after the base substrate is placed on the support. it can. As the base substrate, for example, a heterogeneous substrate such as a sapphire substrate, a SiC substrate, a Si substrate, or a GaAs substrate is often used. The nitride semiconductor crystal grown on the base substrate is separated from the support together with the base substrate, and can be taken out by removing the base substrate by a method such as polishing if necessary (for example, Patent Document 1, Non-Patent Document). Reference 1).

  However, in this method, since a group III nitride semiconductor crystal is grown on different substrates having different lattice constants and thermal expansion coefficients, the obtained group III nitride semiconductor crystal contains many dislocations. When a group III nitride semiconductor crystal having many such dislocations is used, for example, in a light emitting device such as an LED, there is a problem in that non-uniformity occurs in the current flowing in the crystal and the light output becomes non-uniform. It will occur. Therefore, in recent years, it has been strongly desired to establish a technique for efficiently producing a large group III-nitride semiconductor crystal while further improving the quality of the group III nitride semiconductor crystal grown on the substrate.

  Therefore, various techniques for growing a group III nitride semiconductor crystal with dislocations suppressed using a group III nitride semiconductor crystal having dislocations have been studied. For example, the surface of a group III nitride semiconductor crystal having dislocations is covered with a mask having an opening with a width of about 0.1 to 10 μm, and the crystal is grown from the uncovered part through the mask opening, and further on the mask. A crystal growth method characterized by lateral growth has been proposed (see Patent Document 2). It is intended to obtain a thick group III nitride semiconductor crystal by using the crystal having a low dislocation density formed so as to cover the mask in this way as a substrate and further performing crystal growth by the HVPE method or the like.

  As another method, a group III nitride semiconductor crystal having dislocations is sliced along the dislocation direction, and a plurality of sliced crystal pieces are continuously laid in a tile shape so that the dislocation direction is horizontal. A method of manufacturing a group III nitride semiconductor crystal having a large area and a small dislocation density by growing the crystal in a direction perpendicular to the direction of dislocation has also been proposed (see Patent Document 3). Further, it has been proposed that chamfering is performed at the connecting portion between slice crystal pieces laid in a tile shape to form a V-shaped groove to prevent dislocation from occurring in the group III nitride semiconductor crystal to be grown ( (See especially FIG. 14 of patent document 3).

JP 2006-240988 A Japanese Patent Laid-Open No. 10-312971 JP 2006-315947 A

J. Appl. Phys. 37 (1998) 309

  According to the method described in Patent Document 2, it is possible to suppress the dislocation density of crystals grown just above the mask. However, since the dislocation density of the crystal grown in the opening cannot be sufficiently suppressed, the group III nitride semiconductor crystal grown on the crystal eventually has a problem that a region with a low dislocation density and a region with a high dislocation density are mixed. There is.

  According to the method described in Patent Document 3, dislocations existing in the slice crystal piece are difficult to propagate to the group III nitride semiconductor crystal grown on the slice crystal piece. However, this method can be used only when a group III nitride semiconductor crystal is grown in a direction perpendicular to the direction of dislocation, and requires a complicated process of slicing, chamfering, and laying. There is a drawback.

  Therefore, the present inventors provide a method for manufacturing a group III nitride semiconductor crystal having a large area and a small dislocation density in a simpler process in order to solve such problems of the conventional technology. The study was advanced as a purpose.

  As a result of intensive studies to solve the above problems, the present inventors can solve the problems of the prior art by arranging two crystal growth surfaces so as to satisfy a specific condition and growing the crystals. I found out. That is, the following present invention has been provided as means for solving the problems.

[1] A method for producing a group III nitride semiconductor crystal by crystal growth from each of a first crystal growth surface and a second crystal growth surface intersecting at an angle of 10 ° or more and less than 180 °,
The width of the first crystal growth surface and the width of the second crystal growth surface are both 100 μm or more (where the width is a direction perpendicular to the line of intersection of the first crystal growth surface and the second crystal growth surface) The maximum width of
A crystal having a maximum cross-sectional area of 40 mm ² or more perpendicular to both the first crystal growth surface and the second crystal growth surface is crystal growth only from the first crystal growth surface and the second crystal growth surface. A method for producing a group III nitride semiconductor crystal, wherein the crystal growth is performed under a crystal growth plane arrangement condition that can be obtained by the following step.
[2] The method for producing a group III nitride semiconductor crystal according to [1], wherein the first crystal growth surface is present in a protruding crystal portion protruding from the second crystal growth surface (hereinafter referred to as “1”). In this specification, it is referred to as a first aspect).
[3] The method for producing a group III nitride semiconductor crystal according to [2], wherein the protruding crystal part has a cylindrical shape.
[4] The protruding crystal part has p crystal growth planes intersecting the second crystal growth plane at an angle of 10 ° to less than 180 ° (where p is an integer of 3 to 8). The method for producing a Group III nitride semiconductor crystal according to [2], wherein
[5] The method for producing a group III nitride semiconductor crystal according to [4], wherein all of the p crystal growth surfaces intersect with the second crystal growth surface at an angle of approximately 90 °.
[6] As described in [4] or [5], p is 4, and each of the p crystal growth planes intersects an adjacent crystal growth plane at an angle of about 270 °. A method for producing a group III nitride semiconductor crystal.
[7] There are a total of m crystal growth surfaces including the first crystal growth surface and the second crystal growth surface (where m is an integer of 3 or more), and the nth crystal growth surface and the (n + 1) th crystal growth surface. In a state where the crystal growth plane intersects at an angle of 10 ° or more and less than 180 ° (where n represents an integer from 1 to m−1), a crystal is grown from each crystal growth surface to obtain III A method for producing a group III nitride semiconductor crystal according to [1], wherein a group nitride semiconductor crystal is produced (hereinafter referred to as a second embodiment in the present specification).
[8] The method for producing a group III nitride semiconductor crystal according to [7], wherein the normal lines of the m crystal growth surfaces are all in a substantially plane.
[9] The method for producing a group III nitride semiconductor crystal according to [8], wherein the first crystal growth surface and the m-th crystal growth surface intersect at an angle of 10 ° or more and less than 180 °. .
[10] The method for producing a group III nitride semiconductor crystal according to any one of [7] to [9], wherein m is an integer of 3 to 10.

[11] A crystal growth surface unit comprising a first crystal growth surface, a second crystal growth surface, and a third crystal growth surface, wherein the first crystal growth surface and the second crystal growth surface are 10 ° or more and 180 °. The second crystal growth surface and the third crystal growth surface intersect at an angle of 10 ° or more and less than 180 °, and the normal line of the first crystal growth surface, By growing a crystal from each crystal growth surface in a state where there are a plurality of crystal growth surface units in which the normal line of the second crystal growth surface and the normal line of the third crystal growth surface are all substantially in the plane, III is obtained. A method for producing a group III nitride semiconductor crystal according to [1], wherein a group nitride semiconductor crystal is produced (hereinafter referred to as a third aspect in the present specification).
[12] The method for producing a group III nitride semiconductor crystal according to [11], wherein the second crystal growth surfaces of the crystal growth surface units are all on the same plane.
[13] The method for producing a group III nitride semiconductor crystal according to [12], wherein the second crystal growth plane of each crystal growth plane unit is present in a single crystal.
[14] A feature of arranging a plurality of crystals including a second crystal growth surface at intervals, and disposing a crystal including the first crystal growth surface and the third crystal growth surface so as to cover each interval from above. The method for producing a group III nitride semiconductor crystal according to any one of [11] to [13].
[15] A plurality of crystals including the second crystal growth surface are continuously arranged without a gap, and a crystal including the first crystal growth surface and the third crystal growth surface is installed so as to cover each junction from above. The method for producing a group III nitride semiconductor crystal according to any one of [11] to [13], wherein:
[16] The first crystal growth planes of each crystal growth plane unit are all substantially parallel, the second crystal growth planes of each crystal growth plane unit are all substantially parallel, and the third crystal of each crystal growth plane unit The method for producing a group III nitride semiconductor crystal according to any one of [11] to [15], wherein all the growth surfaces are substantially parallel.
[17] Any one of [11] to [16], wherein the first crystal growth surface and the second crystal growth surface of each crystal growth surface unit intersect at an angle of approximately 90 °. A method for producing a Group III nitride semiconductor crystal.
[18] As described in any one of [11] to [17], the second crystal growth surface and the third crystal growth surface of each crystal growth surface unit intersect at an angle of approximately 90 °. A method for producing a Group III nitride semiconductor crystal.
[19] The group III according to any one of [11] to [18], wherein m crystal growth surface units are arranged in parallel (where m is an integer of 2 or more). A method for producing a nitride semiconductor crystal.
[20] The third crystal growth surface of the nth unit and the first crystal growth surface of the (n + 1) th unit are present in a single crystal (where n is an integer from 1 to m−1). The method for producing a group III nitride semiconductor crystal according to [19].
[21] The crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit are separate crystals and are not in contact with each other (where n is from 1 to m−1) Or a group III nitride semiconductor crystal according to [19] or [20].
[22] The crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit are separate crystals and are in contact with each other (where n is from 1 to m−1) Or a group III nitride semiconductor crystal according to [19] or [20].

[23] The group III according to any one of [1] to [22], wherein the crystal having the first crystal growth surface and the crystal having the second crystal growth surface are separate crystals. A method for producing a nitride semiconductor crystal.
[24] The crystal according to [23], wherein the crystal having the first crystal growth surface and the crystal having the second crystal growth surface are arranged so as to be in contact with each other in the same plane as the second crystal growth surface. A method for producing a Group III nitride semiconductor crystal.
[25] The method for producing a group III nitride semiconductor crystal according to any one of [1] to [20], wherein each of the crystal growth planes is in a single crystal.
[26] The method according to [25], wherein the single crystal is produced by growing a group III nitride semiconductor crystal after covering a part of the group III nitride semiconductor crystal with a mask material. A method for producing a Group III nitride semiconductor crystal.
[27] The method for producing a group III nitride semiconductor crystal according to [26], wherein a surface to be the second crystal growth surface is covered with a mask material.
[28] The group III nitride semiconductor crystal according to any one of [1] to [27], wherein a dislocation density of the second crystal growth surface is 1 × 10 ⁸ cm ⁻² or more. Production method.
[29] The dislocation density of the crystal growth surface other than the second crystal growth surface is 1 × 10 ⁶ cm ⁻² or less, [III] according to any one of [1] to [28] A method for producing a group nitride semiconductor crystal.
[30] The method further includes a step of cutting out a region grown from the crystal growth surface other than the second crystal growth surface in the group III nitride semiconductor crystal grown by the crystal growth. 29] The manufacturing method of the group III nitride semiconductor crystal as described in any one of 29.
[31] The method according to any one of [1] to [29], further including a step of cutting out a region grown from the first crystal growth surface of the group III nitride semiconductor crystal grown by the crystal growth. A method for producing a Group III nitride semiconductor crystal according to Item.

[32] A group III nitride semiconductor crystal produced by the production method according to any one of [1] to [31] and having a maximum cross-sectional area of 40 mm ² or more.
[33] A group III nitride semiconductor crystal produced by the production method according to [31] and having a maximum cross-sectional area of 40 mm ² or more.

[34] having a first crystal growth surface and a second crystal growth surface intersecting at an angle of 10 ° or more and less than 180 °,
The width in the direction perpendicular to the line of intersection between the first crystal growth surface and the second crystal growth surface is 100 μm or more in both the first crystal growth surface and the second crystal growth surface,
A crystal having a maximum cross-sectional area of 40 mm ² or more perpendicular to both the first crystal growth surface and the second crystal growth surface is crystal growth only from the first crystal growth surface and the second crystal growth surface. A base substrate for growing a group III nitride semiconductor crystal, wherein the first crystal growth surface and the second crystal growth surface are arranged so as to be obtainable by:
[35] The base substrate for growing a group III nitride semiconductor crystal according to [34], wherein the first crystal growth surface is present in a protruding crystal portion protruding from the second crystal growth surface.
[36] There are a total of m crystal growth surfaces including the first crystal growth surface and the second crystal growth surface (where m is an integer of 3 or more), and the nth crystal growth surface and the (n + 1) th crystal growth surface. The group III nitride according to [34], wherein the crystal growth plane intersects at an angle of 10 ° or more and less than 180 ° (where n represents an integer from 1 to m−1). A base substrate for semiconductor crystal growth.
[37] A crystal growth surface unit composed of a first crystal growth surface, a second crystal growth surface, and a third crystal growth surface, wherein the first crystal growth surface and the second crystal growth surface are 10 ° or more and 180 °. The second crystal growth surface and the third crystal growth surface intersect at an angle of 10 ° or more and less than 180 °, and the normal line of the first crystal growth surface, The group III nitride according to [32], wherein there are a plurality of crystal growth surface units in which the normal line of the second crystal growth surface and the normal line of the third crystal growth surface are all substantially in a plane. A base substrate for semiconductor crystal growth.
[38] The base substrate for growing a group III nitride semiconductor crystal according to any one of [34] to [37], comprising a single crystal.

  According to the method for producing a group III nitride semiconductor crystal of the present invention, a group III nitride semiconductor crystal having a large area and a small dislocation density can be produced by a simple process. In addition, when the base substrate for growing a group III nitride semiconductor crystal of the present invention is used, a group III nitride semiconductor crystal having a large area and a low dislocation density can be easily produced. Furthermore, the group III nitride semiconductor crystal of the present invention has a large area and a low dislocation density.

It is a perspective view which shows one specific example of a 1st aspect. It is a perspective view which shows one specific example of a 1st aspect. It is a perspective view which shows one specific example of a 1st aspect. It is a perspective view which shows one specific example of a 1st aspect. It is a perspective view which shows one specific example of a 2nd aspect. It is a perspective view which shows one specific example of a 2nd aspect. It is a perspective view which shows one specific example of a 3rd aspect. It is a perspective view which shows one specific example of a 3rd aspect. It is a perspective view which shows one specific example of a 3rd aspect. It is a perspective view for demonstrating the crystal arrangement | positioning of a 3rd aspect. It is a perspective view for demonstrating the manufacturing method of the 2nd aspect using mask material. It is sectional drawing for demonstrating the dislocation of each crystal region manufactured with the manufacturing method of this invention. It is sectional drawing for demonstrating the crystal orientation of each crystal region manufactured with the manufacturing method of this invention. It is a schematic diagram of an HVPE apparatus. FIG. 3 is a perspective view showing the arrangement of crystals in Example 1.

  Hereinafter, the group III nitride semiconductor crystal of the present invention, a method for producing the same, and the base substrate for growing the group III nitride semiconductor crystal will be described in detail. The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Type of group III nitride semiconductor crystals)
The type of group III nitride semiconductor crystal produced by the production method of the present invention is not particularly limited. For example, GaN, InN, AlN, InGaN, AlGaN, AllnGaN, etc. can be mentioned. Preferred is GaN, AlN, AlGaN, AllnGaN, and more preferred is GaN. In the following description, a GaN (gallium nitride) crystal may be described as an example of the group III nitride semiconductor crystal, but the nitride semiconductor crystal that can be employed in the present invention is not limited to this.

(First crystal growth surface and second crystal growth surface)
In the manufacturing method of the present invention, a group III nitride semiconductor crystal is grown from each of the first crystal growth surface and the second crystal growth surface intersecting at an angle of 10 ° or more and less than 180 °.
Both the first crystal growth surface and the second crystal growth surface employed in the present invention are surfaces existing in the same group III nitride semiconductor crystal as the group III nitride semiconductor crystal to be grown. For example, when a gallium nitride crystal is to be grown, two types of surfaces existing in the gallium nitride crystal can be used as a first crystal growth surface and a second crystal growth surface. Examples of combinations of plane orientations of the first crystal growth plane and the second crystal growth plane include (0001) plane and {10-10} plane, (000-1) plane and {10-10} plane, {11- 20} plane and {10-10} plane, {10-11} plane and {10-10} plane, {10-10} plane and (0001) plane, {11-20} plane and (0001) plane, { 10-11} plane and (0001) plane, {10-10} plane and (000-1) plane, {11-20} plane and (000-1) plane, {10-11} plane and (000-1) ) Surface. Among them, (0001) plane and {10-10} plane, (000-1) plane and {10-10} plane, {11-20} plane and {10-10} plane, {10-10} plane And the {10-10} plane, the combination of the {10-11} plane and the {10-10} plane is preferable in that it is easy to obtain a high-quality, large group III nitride semiconductor crystal. The plane orientation of each crystal plane may be shifted from the above crystal plane by an arbitrary angle. Preferably, it is in the range of plus or minus 10 ° from any crystal plane.

  The first crystal growth surface and the second crystal growth surface may exist in the same crystal or may exist in different crystals. When the first crystal growth surface and the second crystal growth surface exist in different crystals, the first crystal growth surface and the second crystal growth surface intersect at an angle of 10 ° to less than 180 °. Two crystals are arranged in At this time, the two crystals may be arranged so that their orientations coincide with each other, or may be arranged so that their orientations are shifted. If the two crystals are arranged so that their orientations coincide with each other, it is preferable in that the crystal orientations of the obtained crystals are aligned.

  When the first crystal growth surface and the second crystal growth surface exist in different crystals, there is an advantage that dislocations in the group III nitride semiconductor crystal to be grown can be more easily suppressed. For example, even if one surface of a crystal having a high dislocation density is selected as the second crystal growth surface, the surface of the crystal having a low dislocation density is selected and arranged as the first crystal growth surface. It becomes easier to suppress dislocations in the group III nitride semiconductor crystal to be formed. Since crystals with a low dislocation density can be obtained with a relatively small size, the above arrangement can be easily realized by placing a small crystal with a low dislocation density on a crystal with a large area and a high dislocation density. can do. That is, the above arrangement can be easily realized by arranging the crystal having the first crystal growth surface so as to be in contact with the crystal having the second crystal growth surface in the same plane as the second crystal growth surface. .

  On the other hand, when the first crystal growth surface and the second crystal growth surface exist in the same crystal, the crystal is different from the case where each crystal growth surface exists in another crystal. It is not necessary to arrange to satisfy. For this reason, if a crystal having no deflection or twist is used, there is an advantage that the first crystal growth surface and the second crystal growth surface can be arranged in a state where there is no misalignment. Even when a crystal having dislocations is used, dislocations in the crystal plane do not propagate in growth in a direction perpendicular to the dislocations by setting at least one crystal growth surface in a direction parallel or substantially parallel to the dislocations. Therefore, it is possible to grow a group III nitride semiconductor crystal having a low dislocation density. In this specification, “substantially parallel” means 0 ° ± 30 °, preferably 0 ° ± 20 °, more preferably 0 ° ± 10 °, and still more preferably 0 °. ± 5 °.

  The first crystal growth surface and the second crystal growth surface can be smoothed by a method such as polishing or etching.

  The widths of the first crystal growth surface and the second crystal growth surface are both 100 μm or more. The width here means the maximum width in the direction perpendicular to the line of intersection of the first crystal growth surface and the second crystal growth surface. Moreover, the intersection line here does not necessarily need to exist, and may be a virtual line segment assumed at a place where two crystal growth planes intersect. For example, a portion where two crystal growth surfaces intersect may be gently curved. The width of the first crystal growth surface and the second crystal growth surface is preferably 100 μm or more, more preferably 150 μm or more, further preferably 200 μm or more, and particularly preferably 250 μm or more. The upper limit is not particularly limited, but can be, for example, 5000 μm or less. When the first crystal growth surface having a relatively low dislocation density and the second crystal growth surface having a relatively high dislocation density are employed, it is preferable to make the width of the first crystal growth surface as large as possible.

  The crossing angle between the first crystal growth surface and the second crystal growth surface is not less than 10 ° and less than 180 °. If the crossing angle is less than 10 °, the group III nitride semiconductor crystal is difficult to grow from the first crystal growth surface and the second crystal growth surface, and defects are likely to occur. The crossing angle is preferably 20 ° or more, more preferably 30 ° or more, further preferably 45 ° or more, and particularly preferably 60 ° or more. By increasing the crossing angle, a group III nitride semiconductor crystal with fewer dislocations can be grown in a time-efficient manner. The crossing angle is preferably 160 ° or less, more preferably 140 ° or less, further preferably 120 ° or less, and particularly preferably 100 ° or less. By reducing the crossing angle, the growth amount of the group III nitride semiconductor crystal having relatively large dislocations can be suppressed.

  The plane orientations and crossing angles of the first crystal growth surface and the second crystal growth surface can be selected in appropriate combination. That is, in order to make it easier to effectively suppress crystal defects (dislocations) propagating from the second crystal growth surface, the selection is made so that the first crystal growth surface can be grown so as to cover the second crystal growth surface. Is preferable. As a preferred combination example of the plane orientations and the crossing angles of the first crystal growth surface and the second crystal growth surface, an aspect in which the crossing angle between the (0001) plane and the {10-10} plane is 90 °, (000-1 ) Plane and the {10-10} plane are 90 °, the {11-20} plane and the {10-10} plane are 90 °, and the {10-11} plane And an angle of intersection between the {10-10} plane and 120 ° or 60 °.

(Conditions surrounding the first crystal growth surface and the second crystal growth surface)
In the manufacturing method of the present invention, a group III nitride semiconductor crystal is formed under conditions that allow a group III nitride semiconductor crystal of a large area to be manufactured by crystal growth from the first crystal growth surface and the second crystal growth surface. Grow. That is, in the present invention, a crystal having a maximum cross-sectional area of 40 mm ² or more perpendicular to both the first crystal growth surface and the second crystal growth surface is grown from the first crystal growth surface and the second crystal growth surface. The crystal growth is performed under the crystal growth plane arrangement condition that can be obtained only by the above method. The maximum cross-sectional area of the crystal that can be grown is preferably 40 mm ² or more, more preferably 60 mm ² or more, further preferably 80 mm ² or more, and particularly preferably 100 mm ² or more.

The maximum cross-sectional area of a crystal that can be grown is not necessarily determined only by the plane orientation and the crossing angle of the first crystal growth surface and the second crystal growth surface, but the crystal grows from the first crystal growth surface and the second crystal growth surface. It may be affected by obstacles in the direction of orientation, the state of arrangement of other crystal growth surfaces, and the nature of the crystal. For example, it is physically impossible to grow a group III nitride semiconductor crystal having a cross-sectional area of 40 mm ² or more with obstacles in the direction of crystal growth from the first crystal growth surface and the second crystal growth surface. In some cases, even if such an obstacle does not exist at the start of crystal growth, a crystal growing from another crystal growth surface prevents crystal growth from the first crystal growth surface and the second crystal growth surface and is 40 mm ² or more. In some cases, it is impossible to grow a group III nitride semiconductor crystal having a cross-sectional area of. In the present invention, a group III nitride semiconductor crystal is grown under conditions free from such obstacles.

Even if there is no obstacle, there may be a case where a group III nitride semiconductor crystal having a cross-sectional area of 40 mm ² or more cannot be grown from the first crystal growth surface and the second crystal growth surface. For example, in the V-shaped groove described in FIG. 14 of the above Japanese Patent Laid-Open No. 2006-315947, a group III nitride semiconductor crystal is facet grown from two crystal growth surfaces constituting the slope of the V-shaped groove. As described above, the dislocation does not grow after forming a loop and disappears. As a result, a group III nitride semiconductor crystal having a cross-sectional area of 40 mm ² or more cannot be obtained from the two crystal growth surfaces. Unlike the above embodiment, the manufacturing method of the present invention produces a group III nitride semiconductor crystal under conditions that allow growth of a crystal having a cross-sectional area of 40 mm ² or more from the first crystal growth surface and the second crystal growth surface. It is something to grow.

  In the present invention, a group III nitride semiconductor crystal is grown using a crystal growth surface arranged so as to satisfy the conditions of the manufacturing method of the present invention. The specific arrangement state of the crystal and the crystal growth surface is not particularly limited as long as it satisfies the conditions of the production method of the present invention, but as a preferable arrangement pattern of the first crystal growth surface and the second crystal growth surface, the following Three aspects can be mentioned. Note that the following three aspects should not be clearly distinguished from each other, and there may be specific examples belonging to a plurality of aspects. In the present invention, it is also possible to adopt a specific example in which a plurality of aspects are combined.

(First aspect)
A 1st aspect is an aspect in which the 1st crystal growth surface exists in the protrusion crystal | crystallization part which protrudes from the 2nd crystal growth surface. In this aspect, it is preferable that the second crystal growth surface is larger than the first crystal growth surface because a crystal having a large area and a small dislocation density can be efficiently obtained from a small size crystal.
The shape of the protruding crystal part is not particularly limited, and may be, for example, a cylindrical shape or a prismatic shape. In the case of a prismatic shape, it may be a quadrangular prism shape including a rectangular parallelepiped or a rectangular parallelepiped, a pentagonal prism shape, a hexagonal prism shape, or an octagonal prism shape. Preferred is a quadrangular prism or hexagonal column for reasons of workability and ease of combination. Any one or more of the surfaces of the protruding crystal portion intersecting with the second crystal growth surface (as described in FIG. 3 below) becomes the first crystal growth surface.

  FIG. 1 illustrates a case where the protruding crystal part 10 is a rectangular parallelepiped. The surface 1 existing in the protruding crystal part 10 intersects the surface 2 at an angle of approximately 90 °. The vertical width of the surface 1 and the horizontal width of the surface 2 are in a range satisfying the conditions of the present invention, and the surface 1 is the first crystal growth surface of the present invention and the surface 2 is the first of the present invention. It plays a role as a crystal growth plane. In the present specification, the term “approximately 90 °” means 90 ° ± 10 °, preferably 90 ° ± 7 °, and more preferably 90 ° ± 5 °. Further, in the present specification, when an angle other than 90 ° is described after the abbreviation, it is interpreted in the same manner as in the case of 90 °.

  FIG. 2 illustrates a state in which the rectangular projecting crystal portion 10 is arranged so as to bisect the upper surface of a wide crystal. Here, the surface 1 serves as the first crystal growth surface of the present invention, and the surface 2 serves as the second crystal growth surface of the present invention. The relationship between the surface 3 and the surface 4 is the same as the relationship between the surface 1 and the surface 2, and the surface 3 serves as the first crystal growth surface of the present invention, and the surface 4 serves as the second crystal growth surface of the present invention. Fulfill. If the arrangement of FIG. 2 is adopted, a group III nitride semiconductor crystal with few dislocations can be grown more efficiently.

  FIG. 3 shows a state in which a rectangular parallelepiped protruding crystal portion 10 is arranged at the center of the upper surface of a wide crystal. Here, the surface 1 serves as the first crystal growth surface of the present invention, and the surface 2 serves as the second crystal growth surface of the present invention. Further, the three side surfaces other than the surface 1 existing in the protruding crystal part 10 can also serve as the first crystal growth surface. If the arrangement of FIG. 3 is employed, a group III nitride semiconductor crystal with few dislocations can be grown more efficiently.

  The projecting crystal part of the rectangular parallelepiped in FIG. 3 can be replaced with a projecting crystal part having a polygonal column shape, a cylindrical shape, or an elliptical column shape. In the case of changing to a polygonal columnar projecting crystal portion, it can be configured to have p crystal growth surfaces that intersect the second crystal growth surface at an angle of 10 ° or more and less than 180 °. Here, p is an integer of 3 or more, and p is preferably an integer of 3 to 8, and more preferably an integer of 4 to 6. Further, all of the p crystal growth planes can be configured to intersect the second crystal growth plane at an angle of approximately 90 °. The protruding crystal part of FIG. 3 shows a state where p is 4 and p crystal growth planes intersect with adjacent crystal growth planes at an angle of about 270 °.

  FIG. 4 illustrates a case where the protruding crystal portion 10 is formed of a hexagonal columnar crystal, and the crystal 11 on which the protruding crystal portion is installed is the same kind of hexagonal columnar crystal. An example of the hexagonal column crystal here is a gallium nitride crystal. The top surface of the crystal 10 and the top surface of the crystal 11 in FIG. 4 can be either + C plane (Ga plane) or −C plane (N plane), and one is + C plane (Ga plane) and the other is − It can also be a C-plane (N-plane). If the upper surface of the crystal 11 is a -C plane (N plane), it is preferable because the first crystal growth plane can be easily grown relatively with respect to the second crystal growth plane. Further, the plane orientations of the side surface of the crystal 10 and the side surface of the crystal 11 may or may not match. For example, the m-axis of the crystal 10 may coincide with the m-axis of the crystal 11, or the m-axis of the crystal 10 may coincide with the a-axis of the crystal 11, for example. These can be appropriately determined in consideration of growth conditions.

  1 to 4, the protruding crystal part 10 is illustrated as a crystal different from the crystal 11 having the face 2, but the protruding crystal part 10 may be integrated as a part of the crystal having the face 2. 1 to 4 is disposed on the large crystal 11 having the surface 2, the crystal including the projecting crystal portion 10 extends downward and penetrates the large crystal 11. It may be.

(Second aspect)
In the second aspect, there are a total of m crystal growth surfaces including the first crystal growth surface and the second crystal growth surface, and the nth crystal growth surface and the (n + 1) th crystal growth surface are 10 ° or more and less than 180 °. It is the aspect which cross | intersects at the angle of. Here, m represents an integer of 3 or more, and n represents each integer from 1 to m-1. m is preferably an integer of 3 to 10, more preferably an integer of 3 to 8, and further preferably an integer of 3 to 6.

  In the second aspect, it is preferable that the normal lines of the m crystal growth planes are all in a substantially plane. By doing so, it becomes easy to grow a group III nitride semiconductor crystal with fewer dislocations. In the present specification, “substantially in a plane” means that the normal lines of m crystal growth planes all fall within a plane inclined by ± 30 ° from a certain plane, and preferably in a plane inclined by ± 20 °. More preferably, it is a case where it falls within a plane inclined by ± 10 °, and further preferably a case where it falls within a plane inclined by ± 5 °. In addition, as the crystal growth proceeds, a specific inclined surface may appear and the normal of each surface may not be substantially in the plane. However, the normals of the m crystal growth surfaces are in a state before crystal growth. Are preferably substantially in a plane.

  In the second aspect, the n-th crystal growth plane and the (n + 1) -th crystal growth plane intersect at an angle of 10 ° to less than 180 ° (n is an integer from 1 to m−1), but the first crystal The growth surface and the m-th crystal growth surface may also intersect at an angle of 10 ° or more and less than 180 °. By doing so, a closed region defined by the m crystal growth planes is formed, and a group III nitride semiconductor crystal can be grown in the region. By growing a crystal in such a closed region, the space utilization efficiency can be increased.

  FIG. 5 illustrates a state in which the surface 1 and the surface 2 intersect with each other at an angle of about 90 ° via the intersection line 15 and the surface 2 and the surface 3 intersect with each other at an angle of about 90 °. . The length (width) of the surface 1 in the direction perpendicular to the intersecting line 15 and the length (width) of the surface 2 in the direction perpendicular to the intersecting line 15 are in a range satisfying the conditions of the present invention. 1 serves as a first crystal growth surface of the present invention, and surface 2 serves as a second crystal growth surface of the present invention. The relationship between the surface 2 and the surface 3 is the same as the relationship between the surface 1 and the surface 2. The surface 1, the surface 2, and the surface 3 are included in different crystals, respectively, and these three crystals are disposed on the support 20 as illustrated.

  FIG. 6 is obtained by additionally installing a crystal having a surface 4 in FIG. The surface 4 intersects with the surface 3 at an angle of approximately 90 °, and is disposed so as to intersect with the surface 1 at an angle of approximately 90 °. By doing so, a closed region defined by the surface 1, the surface 2, the surface 3, and the surface 4 is formed, and a group III nitride semiconductor crystal can be grown at least in this region. Space can be used effectively. In FIG. 6, a closed region is formed by four surfaces. However, a closed region can be formed by three surfaces, and a closed region can be formed by five or more surfaces. It is.

  Although the surface of the support 20 in FIGS. 5 and 6 does not function as a crystal growth surface, a crystal having a crystal growth surface can be used instead of the support 20. 5 and 6, the crystal growth planes intersect at an angle of approximately 90 °, but each intersection angle can be appropriately changed within a range of 10 ° to less than 180 °. However, in the case of FIG. 6, adjustment is made so that the sum of the four intersection angles is 360 ° in order to form a closed region. 5 and 6 show an embodiment in which a plurality of crystals are used, these may be constituted by a single crystal.

(Third aspect)
A 3rd aspect is an aspect which has multiple crystal growth surface units which consist of a 1st crystal growth surface, a 2nd crystal growth surface, and a 3rd crystal growth surface. In this crystal growth surface unit, the first crystal growth surface and the second crystal growth surface intersect at an angle of 10 ° or more and less than 180 °, and the second crystal growth surface and the third crystal growth surface are 10 ° or more. Cross at an angle of less than 180 °. Further, the normal lines of the first crystal growth surface, the second crystal growth surface, and the third crystal growth surface are all in a substantially plane. A group III nitride semiconductor crystal can be produced by growing a crystal from each crystal growth surface of each unit with a plurality of such crystal growth surface units installed.

  FIG. 7 illustrates an example in which the third aspect is embodied. Surfaces 1, 2 and 3 function as a first crystal growth surface, a second crystal growth surface and a third crystal growth surface of the present invention, respectively, and these three surfaces form one crystal growth surface unit 21. ing. Further, the surface 4, the surface 5, and the surface 6 also function as the first crystal growth surface, the second crystal growth surface, and the third crystal growth surface of the present invention, respectively, and these three surfaces are another crystal growth surface unit. 22 is formed.

  In the third aspect, the second crystal growth planes of the crystal growth plane units can all be on the same plane. That is, in FIG. 7, the surface 2 of the crystal growth surface unit 21 and the surface 5 of the crystal growth surface unit 22 can be positioned in the same plane. Such a state is easily formed by placing, for example, a crystal 12 having a plane 1, a crystal 13 having a plane 3 and a plane 4, and a crystal 14 having a plane 6 on a large crystal 11 having a flat upper surface. can do. At this time, the crystal 11 is not necessarily a single crystal, and a plurality of crystals having the same thickness may be laid in the lateral direction.

  In the third aspect, all the first crystal growth surfaces of each crystal growth surface unit are substantially parallel, all the second crystal growth surfaces of each crystal growth surface unit are substantially parallel, and each crystal growth surface unit has a The third crystal growth planes can be installed so as to be substantially parallel. That is, in FIG. 7, the surface 1 of the crystal growth surface unit 21 and the surface 4 of the crystal growth surface unit 22 are made substantially parallel, similarly, the surface 2 and the surface 5 are made substantially parallel, and the surface 3 and the surface 6 are made substantially parallel. be able to. By installing in this way, there is an advantage that the properties of the group III nitride semiconductor crystal grown in each unit can be made more uniform.

  In the third aspect, the intersection angle between the first crystal growth plane and the second crystal growth plane of each crystal growth plane unit, and the intersection angle between the second crystal growth plane and the third crystal growth plane of each crystal growth plane unit are: Each can be determined independently. However, when it is necessary to make the properties of the group III nitride semiconductor crystal grown in each unit more uniform, the intersection angles of the first crystal growth surface and the second crystal growth surface of each crystal growth surface unit should be matched. In addition, it is preferable that the second crystal growth surface and the third crystal growth surface of each crystal growth surface unit have the same intersection angle. In FIG. 7, the first crystal growth surface and the second crystal growth surface of each crystal growth surface unit intersect at an angle of approximately 90 °, and the second crystal growth surface and the third crystal growth surface of each crystal growth surface unit are approximately. It intersects at an angle of 90 °.

  In FIG. 7, the crystal growth surface unit composed of the surface 1, the surface 2, and the surface 3 and the crystal growth surface unit composed of the surface 4, the surface 5, and the surface 6 are arranged in parallel in the horizontal direction. Crystal growth plane units can be additionally arranged in parallel in the horizontal direction. For example, when the crystal growth surface units are referred to as a first unit and a second unit in order from the end, if there are m units, they are arranged in parallel up to the mth unit. At this time, it is preferable that the third crystal growth surface of the nth unit and the first crystal growth surface of the (n + 1) th unit exist in a single crystal. Here, m is an integer of 2 or more, and n is an integer from 1 to m-1. In the example shown in FIG. 7, the surface 3 of the crystal growth surface unit (first unit) 21 and the surface 4 of the crystal growth surface unit (second unit) 22 are present in a single crystal. By adopting such a configuration, the crystal growth surface can be used efficiently.

  In the third aspect, the crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit can be installed as separate crystals. At this time, the crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit may or may not be in contact with each other. FIG. 8 and FIG. 9 are diagrams showing an arrangement example of the second crystal growth surface 11a of the first unit, the second crystal growth surface 11b of the second unit, and the crystal 13 connecting these (first unit). The first crystal growth plane and the third crystal growth plane of the second unit are omitted). FIG. 8 shows that the crystal 11a including the second crystal growth surface (surface 2) of the first unit and the crystal 11b including the second crystal growth surface (surface 5) of the second unit are not in contact with each other. 2 shows a state in which the space 16 is arranged with a space therebetween. This state is formed by arranging a plurality of crystals including the second crystal growth surface at intervals and arranging the crystal including the first crystal growth surface and the third crystal growth surface so as to cover each interval from above. can do. In the present invention, a plurality of crystals including the second crystal growth surface are continuously arranged with no space therebetween, and the crystal including the first crystal growth surface and the third crystal growth surface so as to cover each junction from above. It is also preferable to install. 9 shows that the crystal 11a including the second crystal growth surface (surface 2) of the first unit and the crystal 11b including the second crystal growth surface (surface 5) of the second unit are not in contact with each other via the crystal 13. It shows the state that is connected continuously.

(Base substrate manufacturing method)
There is no particular limitation on the method for manufacturing a Group III nitride semiconductor crystal growth base substrate (hereinafter, sometimes simply referred to as a base substrate) having a crystal growth surface arranged to satisfy the conditions of the manufacturing method of the present invention. When using a base substrate made of a plurality of crystals, the base substrate can be manufactured by arranging each crystal so as to satisfy the conditions of the manufacturing method of the present invention as described above. The contact surface of each crystal may be bonded to such an extent that the crystal does not move under the growth conditions of the group III nitride semiconductor crystal. Therefore, as long as the crystal does not move under the growth conditions of the group III nitride semiconductor crystal of the present invention, it is only necessary to place the crystals in an overlapping manner.

  For example, when manufacturing the base substrate according to the third aspect, as shown in FIG. 10, the crystals F1, F2, F3, F4 including the second crystal growth surface are arranged at intervals, and the intervals are set. The crystal D1, D2, D3 including the first crystal growth surface and the third crystal growth surface can be easily manufactured so as to cover from above. At this time, the crystals F1, F2, F3, and F4 may be continuously arranged without a space therebetween, and the crystals D1, D2, and D3 may be installed so as to cover the respective joints from above. By manufacturing the base substrate in this manner, the space and the junctions existing between the crystals F1, F2, F3, and F4 do not appear at all on the crystal growth surface of the present invention even though the base substrate has a large area. Therefore, a group III nitride semiconductor crystal with few defects can be grown on the crystal growth surface. In particular, dislocations are likely to occur in a crystal grown on a region such as a junction formed when a crystal including the second crystal growth surface is arranged. By disposing the crystal so as to cover the junction, It is possible to efficiently suppress the occurrence of dislocations.

The base substrate used in the manufacturing method of the present invention can also be manufactured using a mask material. In particular, when a base substrate made of a single crystal is manufactured, it is preferable to manufacture using a mask material. For example, when the base substrate shown in FIG. 5 is manufactured, a mask material 19 is provided on the upper surface of the group III nitride semiconductor crystal 11 as shown in FIG. 11, and the region not covered with the mask is directed upward. Crystals can be grown. Even when the dislocation density in the vertical direction of the crystal 11 used for manufacturing the base substrate is high, the side surface of the crystal grown upward from the region not covered with the mask (that is, the surface 1, surface in FIG. 5) 2, plane 3) is substantially parallel to the vertical dislocation. For this reason, even if a group III nitride semiconductor crystal is grown in the horizontal direction from these side surfaces in accordance with the manufacturing method of the present invention, dislocations are unlikely to propagate to the crystal grown on the region above the mask material 19. In addition, after manufacturing the base substrate, the mask material 19 may be removed or left as it is. By leaving the mask material 19 as it is without being removed, it is possible to control the crystal so that it does not grow from the region covered with the mask material when the target group III nitride semiconductor crystal is grown. In the present invention, for example, SiO ₂ , SiC, Al ₂ O ₃ , Si ₃ N ₄ , BN, C, Pt, Ir, W or the like can be used as a mask material.

(Crystal growth)
In the manufacturing method of the present invention, a group III nitride semiconductor crystal is grown using a base substrate having a crystal growth surface arranged so as to satisfy the conditions of the present invention.
The crystal growth method is not particularly limited, and hydride vapor phase growth method (HVPE method), ammonothermal method, metal organic chemical vapor deposition method (MOCVD method), molecular beam epitaxy method (MBE method), liquid phase epitaxy. -Method (LPE method), sublimation method and the like can be appropriately selected and employed. Among these, the HVPE method, the ammonothermal method, and the LPE method are preferable because they easily grow bulk crystals.

  By growing a group III nitride semiconductor crystal using a base substrate having a crystal growth surface arranged to satisfy the conditions of the present invention, even if dislocations exist in the base substrate, the dislocations A crystal with significantly suppressed propagation can be obtained. For example, when a group III nitride semiconductor crystal is grown using the base substrate shown in FIG. 2, the crystal grows upward from the surfaces 2 and 4 as shown in FIG. As S3 is formed, a crystal grows from the surfaces 1 and 3 in the horizontal direction, and a crystal grows from the upper surface of the crystal 10 in the upward direction, thereby forming a crystal region S1. At this time, even if there are many dislocations 17 in the crystal 11 having the face 2 and the face 4, the dislocation propagates only to the crystal regions S2 and S3 growing from the face 2 and the face 4. That is, since the crystal region S1 formed above the boundary surface 18 does not include a region crystallized in the direction perpendicular to the dislocation, no defect propagates. Therefore, by cutting out this portion, a high-quality group III nitride semiconductor crystal having a low dislocation density can be obtained.

In FIG. 12, the angle θ between the surface 2 and the boundary surface 18 is determined by the growth rate (R1) of the crystal growing from the surface 1 in the lateral direction and the growth rate (R2) of the crystal growing from the surface 2 upward. Determined by the ratio of If the speed ratio (R1 / R2) is large, the angle θ is small, and if the speed ratio (R1 / R2) is small, the angle θ is large. In order to efficiently manufacture the crystal region S1 having a low dislocation density, the first crystal growth surface and the second crystal growth surface are selected so that the speed ratio (R1 / R2) is increased, and the angle θ is decreased. preferable. Specifically, in the case of the gas phase method, the ratio of the group III element to the group V element in the source gas and the growth temperature are adjusted, and in the case of the ammonothermal method, the temperature, pressure, mineralizer The speed ratio (R1 / R2) can be increased by adjusting the type and density.

  The situation described with reference to FIG. 12 applies not only to dislocations but also to crystal orientations. For example, as shown in FIG. 13, when the crystal orientation of the crystal 11a having the face 2 is different from the crystal orientation of the crystal 11b having the face 4, the crystal orientation of the crystal 11a is increased in the region S2 when the crystal is grown according to the present invention. A crystal having the crystal orientation of the crystal 11b is formed in the region S3. On the other hand, in the region S1, a crystal having the crystal orientation of the crystal 10 is formed without being affected by these crystal orientations. That is, it is preferable to cut out the region S1 because a high-quality group III nitride semiconductor crystal having a uniform crystal orientation can be obtained.

The situation regarding dislocations and crystal orientations described with reference to FIG. 12 can be applied to the case where crystal growth is performed using another base substrate. For example, even when the dislocation density on the second crystal growth surface of each of the underlying substrates described above is relatively high, a group III nitride semiconductor crystal having a low dislocation density can be obtained by the production method of the present invention. is there. For example, the dislocation density of the second crystal growth surface is 1 × 10 ⁸ cm ⁻² or more and the dislocation density of the crystal growth surface other than the second crystal growth surface is 1 × 10 ⁶ cm ⁻² or less. Below, it is possible to grow a group III nitride semiconductor crystal having a low dislocation density.

(Manufacturing equipment and crystal growth conditions)
In the present invention, a production apparatus capable of growing a group III nitride semiconductor crystal can be appropriately selected and used. Hereinafter, a hydride vapor phase epitaxy (HVPE) manufacturing apparatus will be described with reference to FIG. 14 as an example of a preferable manufacturing apparatus for carrying out the manufacturing method of the present invention.

1) Basic Structure The manufacturing apparatus shown in FIG. 14 includes in a reactor 100 a susceptor 108 for placing seeds and a reservoir 106 into which a group III nitride semiconductor material to be grown is placed. In addition, introduction pipes 101 to 105 for introducing gas into the reactor 100 and an exhaust pipe 109 for exhausting are installed. Further, a heater 107 for heating the reactor 100 from the side surface is installed.

2) Reactor material, gas type of ambient gas As the material of the reactor 100, quartz, sintered boron nitride, stainless steel, or the like is used. A preferred material is quartz. The reactor 100 is filled with atmospheric gas in advance before starting the reaction. Examples of the atmospheric gas (carrier gas) include inert gases such as hydrogen, nitrogen, He, Ne, and Ar. These gases may be mixed and used.

3) Material and shape of susceptor, distance from growth surface to susceptor The material of the susceptor 108 is preferably carbon, and more preferably the surface is coated with SiC. The shape of the susceptor 108 is not particularly limited as long as the growth base substrate used in the present invention can be installed. However, it is preferable that no structure exists near the crystal growth surface during crystal growth. . If there is a structure that can grow in the vicinity of the crystal growth surface, a polycrystal adheres to the structure, and HCl gas is generated as a product to adversely affect the crystal to be grown. The contact surface between the seed and the susceptor 108 is preferably 1 mm or more away from the crystal growth surface of the seed, more preferably 3 mm or more, and still more preferably 5 mm or more.

4) Reservoir The reservoir 106 is charged with the raw material of the group III nitride semiconductor to be grown. Specifically, the raw material which becomes a group III source is put. Examples of the raw material to be a group III source include Ga, Al, and In. A gas that reacts with the raw material put in the reservoir 106 is supplied from an introduction pipe 103 for introducing the gas into the reservoir 106. For example, when a raw material that is a group III source is put in the reservoir 106, HCl gas can be supplied from the introduction pipe 103. At this time, the carrier gas may be supplied from the introduction pipe 103 together with the HCl gas. Examples of the carrier gas include hydrogen, nitrogen, an inert gas such as He, Ne, and Ar. These gases may be mixed and used.

5) Nitrogen source (ammonia), separate gas, dopant gas From the introduction pipe 104, a raw material gas serving as a nitrogen source is supplied. Usually, NH ₃ is supplied. A carrier gas is supplied from the introduction pipe 101. As the carrier gas, the same carrier gas supplied from the introduction pipe 104 can be exemplified. This carrier gas also has an effect of separating the source gas nozzle and preventing the polycrystal from adhering to the nozzle tip. A dopant gas can also be supplied from the introduction pipe 102. For example, an n-type dopant gas such as SiH ₄ , SiH ₂ Cl ₂ , or H ₂ S can be supplied.

6) Gas introduction method The gases supplied from the introduction pipes 101 to 104 may be exchanged with each other and supplied from another introduction pipe. In addition, the source gas and the carrier gas serving as a nitrogen source may be mixed and supplied from the same introduction pipe. Further, a carrier gas may be mixed from another introduction pipe. These supply modes can be appropriately determined according to the size and shape of the reactor 100, the reactivity of the raw materials, the target crystal growth rate, and the like.

7) Location of Exhaust Pipe The gas exhaust pipe 109 can be installed on the top, bottom, and side surfaces of the reactor inner wall. From the viewpoint of dust removal, it is preferably located below the crystal growth end, and more preferably a gas exhaust pipe 109 is installed on the bottom of the reactor as shown in FIG.

8) Crystal Growth Conditions Crystal growth using the above production apparatus is usually performed at 950 ° C. to 1120 ° C., preferably at 970 ° C. to 1100 ° C., more preferably at 980 ° C. to 1090 ° C., 990 More preferably, the reaction is carried out at a temperature of from 1080 to 1080 ° C. The pressure in the reactor is preferably 10 kPa to 200 kPa, more preferably 30 kPa to 150 kPa, and even more preferably 50 kPa to 120 kPa.

9) Crystal growth rate The growth rate of crystal growth using the above production apparatus varies depending on the growth method, growth temperature, raw material gas supply amount, crystal growth plane orientation, etc., but generally 5 μm / h to 500 μm / The range of h is preferably 10 μm / h or more, more preferably 50 μm / h or more, and further preferably 70 μm or more. In addition to the above, the growth rate can be controlled by appropriately setting the type of carrier gas, the flow rate, the supply port-crystal growth edge distance, and the like.

(Manufactured group III nitride semiconductor crystal)
As described above, according to the manufacturing method of the present invention, a high-quality group III nitride semiconductor crystal having a low dislocation density can be manufactured.
The dislocation density of the group III nitride semiconductor crystal produced by the production method of the present invention is preferably 1 × 10 ⁶ cm ⁻² or less, more preferably 1 × 10 ⁵ cm ⁻² or less. More preferably, it is 10 ⁴ cm ⁻² or less, and even more preferably 1 × 10 ³ cm ⁻² or less. The dislocation density here can be measured using a transmission electron microscope (TEM) method or a cathodoluminescence (CL) method.

According to the production method of the present invention, a group III nitride semiconductor crystal having a large area can be produced. Specifically, it is possible to grow a crystal having an area of the largest surface (main surface) of 40 mm ² or more, and a group III nitride of 100 mm ² or more, further 400 mm ² or more, particularly 2000 mm ² or more. It is also possible to produce a physical semiconductor crystal.

Furthermore, the group III nitride semiconductor crystal produced by the production method of the present invention is also characterized by very little curvature.
The group III nitride semiconductor crystal produced by the production method of the present invention can be used for various applications. In particular, it is useful as a substrate for semiconductor devices such as light emitting diodes of ultraviolet, blue or green, etc., light emitting elements on the relatively short wavelength side such as semiconductor lasers, and electronic devices. It is also possible to obtain a larger group III nitride semiconductor crystal using the group III nitride semiconductor crystal manufactured by the manufacturing method of the present invention as a seed.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
Gallium nitride crystals F1 and F2 having an M plane as a main surface are prepared, arranged so that the + C plane of the crystal F1 and the −C plane of the crystal F2 are bonded, and the crystals F1 and F2 are covered so as to cover the bonded surface. A base substrate was prepared by arranging a gallium nitride crystal D1 having an M plane as a main surface as shown in FIG. The crystal orientation of the crystals F1 and F2 and the crystal orientation of the crystal D1 were shifted by about 0.3 °. The size of the crystals F1 and F2 used here is 20 mm × 8 mm × 0.3 mm, and the size of the crystal D1 is 20 mm × 8 mm × 0.3 mm. The crystal D1 was arranged at the center of the main surface where the crystals F1 and F2 were arranged, and the widths of the crystals F1 and F2 not covered by the crystal D1 were 4 mm.

A substrate was placed on the susceptor 108 of the manufacturing apparatus of FIG. 14, and a gallium nitride crystal was grown on the substrate by the HVPE method. The temperature in the reactor 100 during crystal growth is 1020 ° C., the growth pressure is 1.01 × 10 ⁵ Pa, the partial pressure of the GaCl gas G3 is 1.85 × 10 ² Pa, and the partial pressure of the NH ₃ gas G4 is 7.05. A gallium nitride crystal was grown for 40 hours at a setting of × 10 ³ Pa. As a result, crystals of about 5.4 mm grew in the −c axis direction, and crystals of 5.0 to 5.1 mm grew in the other directions.

  The obtained as-grown crystal was ground and polished using diamond abrasive grains until the M-plane became flat. Then, the difference in twist angle between the crystal grown at a point corresponding to the center point P1 on the upper surface of the crystal D1 and the crystal grown at a point just above the center point P2 of the upper exposed surface of the crystal F2 in FIG. The measurement was performed using (102) plane reflection using an X-ray diffraction measurement apparatus manufactured by Panalical. The twist angle difference Δα was 0.19 °. This means that the twist angle between the crystal grown upward from the upper surface of the crystal D1 and the crystal grown laterally from the crystal D1 was small, which is influenced by the crystal orientation of the crystals F1 and F2. This shows that the lateral crystal growth from the crystal D1 has been performed.

Further, when the dislocation density was measured by the cathodoluminescence (CL) method using a scanning electron microscope (SEM), the dislocation density of the crystal F2 was 2 × 10 ⁶ cm ⁻² , and it grew at a point corresponding to just above P2. The dislocation density of the obtained crystal was 7 × 10 ⁵ cm ⁻² . This indicates that the dislocation of the crystal F2 does not propagate to the crystal grown immediately above it.

(Comparative Example 1)
The crystal growth was performed in the same manner as in Example 1 except that the crystal D1 in Example 1 was not arranged. The twist angle difference Δα between the crystal grown just above the center point of the crystal F1 and the crystal grown just above the center point of the crystal F2 was measured and found to be 1.7 °. Further, the dislocation density of the crystal grown just above the center point of the crystal F2 was measured and found to be 2 × 10 ⁶ cm ⁻² .

  The group III nitride semiconductor crystal manufactured by the manufacturing method of the present invention includes a light emitting element (light emitting diode, laser diode, etc.), an electronic device (rectifier, bipolar transistor, field effect transistor, or HEMT (High Electron Mobility Transistor)). ), Semiconductor sensors (temperature sensors, pressure sensors, radiation sensors, or visible-ultraviolet light detectors), SAW devices (Surface Acoustic Wave Devices), acceleration sensors, MEMS (Micro Electro Mechanical Systems) ) Used for parts, piezoelectric vibrators, resonators or piezoelectric actuators. Further, the substrate of the present invention is effectively used in the production method of the present invention. Therefore, the industrial applicability of the present invention is high.

DESCRIPTION OF SYMBOLS 1-7 Crystal growth surface 10 Protruding crystal | crystallization part 11-14 Crystal 15 Intersection 16 Space 17 Dislocation 18 Boundary surface 19 Mask material 20 Support body 21, 22 Crystal growth surface unit 100 Reactor 101 Carrier gas piping 102 Dopant gas piping 103 Group III source pipe 104 Nitrogen source pipe 105 HCl gas pipe 106 Group III source reservoir 107 Heater 108 Susceptor 109 Exhaust pipe G1 Carrier gas G2 Dopant gas G3 Group III source gas G4 Nitrogen source gas G5 HCl gas D1-D3 Crystal F1 to F4 Crystal S1 to S3 Crystal region P1 Center point of upper surface of crystal D1 P2 Center point of upper exposed surface of crystal F2

Claims (28)

A method for producing a group III nitride semiconductor crystal by crystal growth from each of a first crystal growth surface and a second crystal growth surface intersecting at an angle of 10 ° or more and less than 180 °,
The width of the first crystal growth surface and the width of the second crystal growth surface are both 100 μm or more (where the width is a direction perpendicular to the line of intersection of the first crystal growth surface and the second crystal growth surface) The maximum width of
A crystal having a maximum cross-sectional area of 40 mm ² or more perpendicular to both the first crystal growth surface and the second crystal growth surface is crystal growth only from the first crystal growth surface and the second crystal growth surface. A method for producing a group III nitride semiconductor crystal, wherein the crystal growth is performed under a crystal growth plane arrangement condition that can be obtained by the following step.   2. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the first crystal growth surface is present in a protruding crystal portion protruding from the second crystal growth surface.   The projecting crystal part has p crystal growth planes intersecting the second crystal growth plane at an angle of 10 ° or more and less than 180 ° (where p is an integer of 3 to 8). The method for producing a group III nitride semiconductor crystal according to claim 2.   There are a total of m crystal growth surfaces including the first crystal growth surface and the second crystal growth surface (where m is an integer of 3 or more), and the nth crystal growth surface and the n + 1th crystal growth surface. In a state in which and intersect at an angle of 10 ° or more and less than 180 ° (where n represents an integer from 1 to m−1), a group III nitride is grown by growing a crystal from each crystal growth surface. 2. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the semiconductor crystal is produced.   5. The method for producing a group III nitride semiconductor crystal according to claim 4, wherein the normal lines of the m crystal growth planes are all substantially in a plane.   6. The method for producing a group III nitride semiconductor crystal according to claim 5, wherein the first crystal growth surface and the m-th crystal growth surface intersect at an angle of 10 ° to less than 180 °.   m is an integer of 3-10, The manufacturing method of the group III nitride semiconductor crystal as described in any one of Claims 4-6 characterized by the above-mentioned.   A crystal growth surface unit comprising a first crystal growth surface, a second crystal growth surface, and a third crystal growth surface, wherein the first crystal growth surface and the second crystal growth surface are 10 ° or more and less than 180 °. The second crystal growth surface and the third crystal growth surface intersect at an angle of 10 ° or more and less than 180 °, and the normal line of the first crystal growth surface, the second crystal A group III nitride is formed by growing a crystal from each crystal growth surface in a state where there are a plurality of crystal growth surface units in which the normal line of the growth surface and the normal line of the third crystal growth surface are all substantially in a plane. 2. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the semiconductor crystal is produced.   9. The method for producing a group III nitride semiconductor crystal according to claim 8, wherein the second crystal growth surfaces of the crystal growth surface units are all on the same plane.   A plurality of crystals including a second crystal growth surface are arranged at intervals, and a crystal including the first crystal growth surface and the third crystal growth surface is installed so as to cover each interval from above. 10. A method for producing a group III nitride semiconductor crystal according to 8 or 9.   A plurality of crystals including the second crystal growth surface are continuously arranged without a gap, and a crystal including the first crystal growth surface and the third crystal growth surface is installed so as to cover each junction from above. The method for producing a group III nitride semiconductor crystal according to claim 8 or 9, wherein   The first crystal growth surfaces of each crystal growth surface unit are all substantially parallel, the second crystal growth surfaces of each crystal growth surface unit are all substantially parallel, and the third crystal growth surface of each crystal growth surface unit is The method for producing a group III nitride semiconductor crystal according to any one of claims 8 to 11, wherein all are substantially parallel.   The group III nitride according to any one of claims 8 to 12, wherein the first crystal growth surface and the second crystal growth surface of each crystal growth surface unit intersect at an angle of approximately 90 °. Manufacturing method of semiconductor crystal.   The group III nitride according to any one of claims 8 to 13, wherein the second crystal growth surface and the third crystal growth surface of each crystal growth surface unit intersect at an angle of approximately 90 °. Manufacturing method of semiconductor crystal.   The group III nitride semiconductor crystal according to any one of claims 8 to 14, wherein m crystal growth plane units are juxtaposed (where m is an integer of 2 or more). Production method.   The third crystal growth surface of the nth unit and the first crystal growth surface of the (n + 1) th unit exist in a single crystal (where n is an integer from 1 to m-1). Item 16. A method for producing a Group III nitride semiconductor crystal according to Item 15.   The crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit are separate crystals and are not in contact with each other (where n is an integer from 1 to m−1) The method for producing a group III nitride semiconductor crystal according to claim 15 or 16, wherein:   The crystal having the second crystal growth surface of the nth unit and the crystal having the second crystal growth surface of the (n + 1) th unit are separate crystals and are in contact with each other (where n is an integer from 1 to m−1) The method for producing a group III nitride semiconductor crystal according to claim 15 or 16, wherein:   The group III nitride semiconductor crystal according to any one of claims 1 to 18, wherein the crystal having the first crystal growth surface and the crystal having the second crystal growth surface are separate crystals. Production method.   20. The group III according to claim 19, wherein the crystal having the first crystal growth surface and the crystal having the second crystal growth surface are arranged so as to be in contact with each other in the same plane as the second crystal growth surface. A method for producing a nitride semiconductor crystal.   21. The method according to claim 1, further comprising a step of cutting out a region grown from the crystal growth surface other than the second crystal growth surface in the group III nitride semiconductor crystal grown by the crystal growth. A method for producing a group III nitride semiconductor crystal according to one item.   21. The method according to claim 1, further comprising a step of cutting out a region grown from the first crystal growth surface of the group III nitride semiconductor crystal grown by the crystal growth. A method for producing a group nitride semiconductor crystal. A group III nitride semiconductor crystal produced by the production method according to any one of claims 1 to 22 and having a maximum cross-sectional area of 40 mm ² or more. A group III nitride semiconductor crystal produced by the production method according to claim 22 and having a maximum cross-sectional area of 40 mm ² or more. Having a first crystal growth surface and a second crystal growth surface intersecting at an angle of 10 ° or more and less than 180 °,
The width in the direction perpendicular to the line of intersection between the first crystal growth surface and the second crystal growth surface is 100 μm or more in both the first crystal growth surface and the second crystal growth surface,
A crystal having a maximum cross-sectional area of 40 mm ² or more perpendicular to both the first crystal growth surface and the second crystal growth surface is crystal growth only from the first crystal growth surface and the second crystal growth surface. A base substrate for growing a group III nitride semiconductor crystal, wherein the first crystal growth surface and the second crystal growth surface are arranged so as to be obtainable by:   26. The base substrate for growing a group III nitride semiconductor crystal according to claim 25, wherein the first crystal growth surface exists in a protruding crystal portion protruding from the second crystal growth surface.   There are a total of m crystal growth surfaces including the first crystal growth surface and the second crystal growth surface (where m is an integer of 3 or more), and the nth crystal growth surface and the n + 1th crystal growth surface. And at an angle of 10 ° or more and less than 180 ° (where n represents an integer from 1 to m−1), and the group III nitride semiconductor crystal according to claim 25, Base substrate for growth.   A crystal growth surface unit comprising a first crystal growth surface, a second crystal growth surface, and a third crystal growth surface, wherein the first crystal growth surface and the second crystal growth surface are 10 ° or more and less than 180 °. The second crystal growth surface and the third crystal growth surface intersect at an angle of 10 ° or more and less than 180 °, and the normal line of the first crystal growth surface, the second crystal The group III nitride semiconductor crystal according to claim 32, wherein there are a plurality of crystal growth surface units in which a normal line of the growth surface and a normal line of the third crystal growth surface are all substantially in a plane. Base substrate for growth.

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