JP5515341B2 - Group III nitride crystal growth method - Google Patents

Description

  The present invention relates to a method for growing a large group III nitride crystal that is suitably used as a substrate of a semiconductor device such as a light emitting device or an electronic device.

  Group III nitride crystals such as GaN crystals and AlN crystals are suitably used for substrates of semiconductor devices such as light emitting devices and electronic devices. In order to efficiently manufacture a semiconductor device having high characteristics, a group III nitride crystal having a large size and high crystallinity is required.

  Here, since the group III nitride crystal does not exist in nature, a different type base substrate having a chemical composition different from that of the group III nitride is used as the base substrate for growing the group III nitride crystal. As such a different base substrate, a sapphire substrate, a spinel substrate, a SiC substrate, a GaAs substrate, or the like is preferably used from the viewpoint of a small mismatch in lattice constant with the group III nitride crystal.

  For example, Japanese Patent Laid-Open No. 2004-91278 (hereinafter referred to as Patent Document 1) forms a group III nitride low-temperature deposition buffer layer (for example, an AlN low-temperature deposition buffer layer) on a different base substrate (sapphire substrate). A method for growing a group III nitride crystal (eg, GaN crystal) on a low temperature deposition buffer layer is disclosed. Japanese Patent Laid-Open No. 2004-331453 (hereinafter referred to as Patent Document 2) forms a patterned metal film (for example, a metal Ti film) on a different base substrate (for example, a sapphire substrate, a GaAs substrate, etc.) A method for growing a group III nitride crystal (eg, GaN crystal, AlN crystal, etc.) on a patterned metal film is disclosed. Further, Patent Document 2 forms a patterned metal film (for example, a metal Ti film) on a different kind of base substrate (for example, sapphire substrate, GaAs substrate, etc.), and a buffer film (for example, for example) on the patterned metal film. A method of forming a group III nitride crystal (for example, GaN crystal, AlN crystal, etc.) on the buffer film is disclosed.

  However, a method of forming a patterned metal film and / or buffer layer on a heterogeneous underlying substrate as disclosed in Patent Documents 1 and 2 and growing a group III nitride crystal on the metal film or buffer layer Then, the difference in crystal system and the mismatch of lattice constants cannot be completely relaxed, and strain stress is generated in the grown group III nitride crystal. Further, a strain stress is generated due to a difference in thermal expansion coefficient between the different base substrate and the group III nitride crystal. For this reason, the obtained group III nitride crystal has problems that warp, cracks, crystallinity, crystal axis variation on the crystal growth surface, and the like occur.

  In order to solve the above problem, Japanese Patent Application Laid-Open No. 2008-133151 (hereinafter referred to as Patent Document 3) discloses an arrangement step in which a plurality of seed substrates are arranged while being shifted to the side of the seed substrate, and a plurality of seed substrates. A method of growing a group III nitride crystal on each surface of the substrate, and growing the crystals so that each of the crystals grown on each surface of the plurality of seed substrates is integrated.

  However, in the method of growing a group III nitride crystal on a plurality of seed substrates as disclosed in Patent Document 3, a plurality of seed substrates having at least one side surface of {10-10} plane are arranged. When a group III nitride crystal is grown on the surface (main surface), a {10-10} facet ({10-1f} plane (where f is an integer other than 0) is formed on the crystal growth surface. As a result, there was a problem that a recess was formed on the crystal growth surface, the yield of the group III nitride crystal was reduced, and the dislocation density of the crystal region grown using the facet as the crystal growth surface was increased.

JP 2004-91278 A JP 2004-331453 A JP 2008-133151 A

  An object of the present invention is to solve the above-mentioned problems and to provide a method for growing a large group III nitride crystal having high crystallinity and a flat crystal growth surface.

  The present invention is a group III nitride chip substrate having a main plane and a plurality of side planes, and the normal line at an arbitrary position of the main plane is 1.0 ° or less with respect to the <0001> direction at the position. A plurality of group III nitride chip substrates having an inclination angle θ and each side plane being a {hk- (h + k) 0} plane other than the {10-10} plane (where h and k are integers) are prepared. And a plurality of group III nitride chip substrates, wherein the normal directions of the main planes of the group III nitride chip substrates are parallel to each other and other than the <10-10> direction of the group III nitride chip substrates < a step of arranging side planes adjacent to each other so that hk- (h + k) 0> directions (where h and k are integers) are parallel to each other, and a plurality of arranged group III nitride chip substrates A group III nitride crystal is grown on the main plane of And a method of growing a group III nitride crystal.

  In the group III nitride crystal growth method according to the present invention, the average roughness Ra of each side plane can be 5 nm or less. The main plane can be rectangular.

  According to the method for growing a group III nitride crystal according to the present invention, a method for growing a group III nitride crystal having a large size, high crystallinity, and a flat crystal growth surface can be provided.

It is the schematic which shows an example of the group III nitride chip board | substrate used in the growth method of the group III nitride crystal concerning this invention. Here, (a) shows a schematic perspective view, (b) shows a schematic cross-sectional view at IB-IB of (a), and (c) shows a schematic cross-sectional view at IC-IC of (a). It is the schematic which shows one Embodiment of the growth method of the group III nitride crystal concerning this invention. Here, (a) shows a schematic plan view, and (b) shows a schematic cross-sectional view taken along IIB-IIB in (a). It is the schematic which shows one form of the growth method of the group III nitride crystal which deviates from this invention. Here, (a) shows a schematic plan view, and (b) shows a schematic cross-sectional view taken along IIIB-IIIB in (a). FIG. 3 is a schematic cross-sectional view showing an example of a group III nitride mother crystal used for manufacturing a group III nitride chip substrate in the group III nitride crystal growth method according to the present invention. It is a schematic sectional drawing which shows the other form of the growth method of the group III nitride crystal which deviates from this invention.

  Referring to FIGS. 1 and 2, the method for growing a group III nitride crystal according to the present invention is a group III nitride chip substrate 12 having a main plane 12m and a plurality of side planes 12s, 12t, The normal at an arbitrary position of 12 m has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at that position, and each side plane 12s, 12t is {hk− other than the {10-10} plane. A step of preparing a plurality of group III nitride chip substrates 12 having a (h + k) 0} plane (where h and k are integers). Further, the group III nitride chip substrates 12 are arranged in directions other than the <10-10> directions of the group III nitride chip substrates 12 in which the normal directions of the main plane 12m of each group III nitride chip substrate 12 are parallel to each other. The side planes 12s and 12t are arranged adjacent to each other so that the <hk- (h + k) 0> directions (where h and k are integers) are parallel to each other. Further, the method includes a step of growing a group III nitride crystal 20 on the main plane 12m of the plurality of group III nitride chip substrates 12 arranged. By providing these steps, a large group III crystal with high crystallinity can be obtained.

  Here, referring to FIGS. 1 to 5, group III nitride mother crystal 10, group III nitride substrate 11, group III nitride chip substrate 12 and group III nitride crystal 20 are all hexagonal wurtzite. Since they have an ore-type crystal structure, the planes of these crystals can be generally expressed as {hkil} planes (where h, k, i and l are integers, i = − (h + k)), and The direction of the crystal can generally be expressed as the <hkil> direction (where h, k, i and l are integers, i = − (h + k)). The {hkil} plane means a generic crystal plane including a (hkil) plane and a crystal plane equivalent to the crystal geometry. The <hkil> direction means a generic direction including the [hkil] direction and a crystal geometrically equivalent direction. 1 to 5 do not reflect actual dimensions, and in order to facilitate understanding, in particular, the length of the crystal or the substrate in the thickness direction is drawn larger than the length in other directions. Yes.

  Referring to FIG. 4, as described above, a group III grown on a different underlying substrate such as a sapphire substrate or a GaAs substrate by a conventional crystal growth method, for example, the crystal growth method disclosed in Patent Documents 1 and 2. After the nitride mother crystal 10 is separated from the different base substrate due to strain stress generated by the difference in lattice constant and / or thermal expansion coefficient between the different base substrate and the group III nitride crystal during crystal growth, The crystal growth surface 10g and the {0001} plane 10c are curved (for example, a group III nitride mother crystal grown on a sapphire substrate or a GaAs substrate as a different base substrate and separated from the different base substrate is (0001) The surface has a curved curvature. As a base substrate for growing a group III nitride crystal from the group III nitride mother crystal 10, a plane perpendicular to the <0001> direction at the center of the group III nitride mother crystal 10 is a main plane 11m. A group III nitride substrate 11 is cut out. The <0001> direction at an arbitrary position on the main plane 11m of the group III nitride substrate 11 thus obtained varies greatly depending on the position. When the group III nitride crystal 20 is grown on the group III nitride substrate 11, the group III nitride crystal 20 undergoes epitaxial growth inheriting the crystallinity of the group III nitride substrate 11. 20 differs greatly in the <0001> direction depending on its position. Since the group III nitride crystal 20 has low crystallinity, the characteristics of a semiconductor device using the group III nitride crystal 20 as a substrate are deteriorated.

  In order to grow a large group III nitride crystal 20 having a high crystallinity, the inventors refer to FIGS. 1, 2, and 4 to have a main plane 12m and a plurality of side planes 12s and 12t. The group nitride chip substrate 12 has a normal line at an arbitrary position of the main plane 12m having an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at the position, and the side planes 12s, 12t. Preparing a plurality of group III nitride chip substrates 12 each having a {hk- (h + k) 0} plane other than the {10-10} plane (where h and k are integers), and a plurality of group III nitrides The chip substrate 12 is <hk− (h + k) 0 other than the <10−10> direction of each group III nitride chip substrate 12 in which the normal directions of the main plane 12 m of each group III nitride chip substrate 12 are parallel to each other. > Direction (where h and k Side planes 12s and 12t are arranged adjacent to each other so that they are parallel to each other, and the group III nitride is formed on the main plane 12m of the plurality of group III nitride chip substrates 12 arranged. It was found that a group III nitride crystal 20 having a large size and high crystallinity was grown by growing the physical crystal 20, and the present invention was completed. Details will be described below. 1 to 3, <ND> indicates a normal direction of the main plane 12 m in the group III nitride chip substrate 12.

(Step of preparing a plurality of group III nitride chip substrates)
1 and 4, the method for growing a group III nitride crystal of the present embodiment is a group III nitride chip substrate 12 having a main plane 12m and a plurality of side planes 12s and 12t, and the main plane. The normal at an arbitrary position of 12 m has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at that position, and each side plane 12s, 12t is {hk− other than the {10-10} plane. A step of preparing a plurality of group III nitride chip substrates 12 having a (h + k) 0} plane (where h and k are integers).

  In group III nitride chip substrate 12 prepared in this step, the normal line at an arbitrary position of main plane 12m has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at that position. For this reason, referring to FIG. 2, the normal line at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g parallel to the main plane 12m is formed on the main plane 12m of the group III nitride chip substrate 12. Group III nitride crystal 20 having an inclination angle θc of about 1.0 ° or less with respect to the <0001> direction at that position can be epitaxially grown, and group III nitride crystal 20 with high crystallinity is obtained. From this point of view, the inclination angle θ that the normal line at any position of the main plane 12m of the group III nitride chip substrate 12 has with respect to the <0001> direction at that position is preferably 0.5 ° or less.

  Here, the inclination angle θ that the normal line at an arbitrary position of the main plane 12m has with respect to the <0001> direction at that position (that is, the inclination between the normal line and the <0001> direction at an arbitrary position of the main plane 12m) The angle θ) is synonymous with the inclination angle θ formed by the main plane 12m and the {0001} plane 12c at an arbitrary position, and is measured by the position of the X-ray diffraction peak with respect to the (0002) plane or the (0004) plane. be able to.

  Further, in the group III nitride chip substrate 12 prepared in this step, each side plane 12s, 12t has a {hk- (h + k) 0} plane other than the {10-10} plane (where h and k are integers). ). Here, referring to FIG. 3, when at least one side plane of group III nitride chip substrate 12 is a {10-10} plane, {10-10} plane is a charge neutral plane (nonpolar plane). Among these, when the group III nitride chip substrate 12 is arranged in plural and the group III nitride crystal 20 is grown on the main plane 12m, it is the closest packed plane of atoms and the most stable crystal plane. Since the {10-1f} plane (where f is an integer other than 0), which is the facet 20f of the {10-10} plane, appears on the crystal growth surface 20g, a recess is formed on the crystal growth surface 20g. The yield of the nitride crystal 20 is reduced, and the dislocation density of the crystal region (facet growth crystal region 20fc) grown using the facet 20f as the crystal growth surface is increased. Therefore, in the group III nitride chip substrate 12 of the present embodiment, all of the side planes 12s and 12t are {hk- (h + k) 0} planes (where h and k are the {10-10} planes). Integer).

  Here, in this step, the method for preparing a plurality of group III nitride chip substrates 12 is not particularly limited, and the following method can be used.

  A group III nitride mother crystal is grown on the main surface of a different kind of base substrate such as a sapphire substrate (main surface is (0001) surface), GaAs substrate (main surface is (111) A surface). Thus, generally, after separation from the different base substrate, the crystal growth surface 10g and the {0001} plane 10c as shown in FIG. 4 are curved (for example, grown on a sapphire substrate or GaAs substrate as the different base substrate). A group III nitride mother crystal 10 having a (0001) plane curved concavely is obtained from the group III nitride mother crystal separated from the different base substrate. The growth method of the group III nitride mother crystal 10 is not particularly limited, and a gas phase method such as HVPE (hydride vapor phase epitaxy) method, MOCVD (metal organic chemical vapor deposition) method, sublimation method, or group III A liquid phase method such as a solution method using a solution in which nitrogen is dissolved in an elemental melt is used.

  Referring to FIGS. 1 and 4, a plurality of group III nitride chip substrates 12 having a main plane 12m and a plurality of side planes 12s, 12t are cut out from group III nitride mother crystal 10 obtained. Here, each group III nitride chip substrate 12 has a normal at an arbitrary position of the main plane 12m having an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at that position, and each side plane. Cut out so that 12s and 12t become {hk- (h + k) 0} planes (where h and k are integers) other than the {10-10} plane. There is no restriction | limiting in particular in the method of cutting out, It can cut out by a wire saw, a dicer, electric discharge machining, scribe etc.

  Here, it is ideal that the group III nitride chip substrate 12 is cut out so that each of the side planes 12s and 12t is a predetermined {hk- (h + k) 0} plane other than the {10-10} plane. However, the side planes 12s and 12t actually cut out may have an inclination angle of about 3 ° or less with respect to the {hk− (h + k) 0} plane. However, if the inclination angle of each of the side planes 12s and 12t is about this level, it does not hinder the growth of the group III nitride crystal 20 having a large size, high crystallinity, and a flat crystal growth surface. The inclination angle formed between the normal line of each side plane 12s, 12t and the <hk- (h + k) 0> direction depends on the position of the X-ray diffraction peak with respect to the (10-10) plane or the (11-20) plane. Can be measured.

  Referring to FIGS. 1 and 2, from the viewpoint of growing group III nitride crystal 20 having high crystallinity, main surface 12m of group III nitride chip substrate 12 is preferably flat. Specifically, the average roughness Ra of the main plane 12m is preferably 5 nm or less, and more preferably 2.5 nm or less. The surface roughness Ra of 5 nm or less of the main plane 12m is obtained by subjecting the main plane 12m to treatments such as grinding, polishing (including mechanical polishing and chemical mechanical polishing), dry etching, and wet etching.

  1 and 2, from the viewpoint of growing a group III nitride crystal 20 having a low dislocation density and a high crystallinity on the joint portion of a plurality of group III nitride chip substrates 12, side planes 12s, 12t is preferably flat. Specifically, the surface roughness Ra of the side planes 12s and 12t is preferably 5 nm or less, and more preferably 2.5 nm or less. The surface roughness Ra of 5 nm or less of the side planes 12s and 12t is obtained by subjecting the side planes 12s and 12t to treatments such as grinding, polishing (including mechanical polishing and chemical mechanical polishing), dry etching, and wet etching. It is done.

  Here, the average roughness Ra refers to the arithmetic average roughness Ra specified in JIS K 0601. Specifically, the average roughness Ra is extracted from the roughness curve by the reference length in the direction of the average line, and the average of the extracted portions is determined. This is the value obtained by summing the distance from the line to the roughness curve (absolute value of deviation) and averaging it with the reference length. The average roughness Ra can be measured with an AFM (atomic force microscope).

  Referring to FIG. 1, the shape of main plane 12m of group III nitride chip substrate 12 is not particularly limited as long as it can cover the plane without any gap (planar filling), and is square, rectangular, rhombus , A quadrangle such as a parallelogram, and a hexagon such as a regular hexagon and a parallelogram. From the viewpoint of high workability in manufacturing the group III nitride chip substrate, the shape of the main plane of the group III nitride chip substrate is preferably a right-angled quadrangle such as a square or a rectangle. Furthermore, from the viewpoint that the directionality of the group III nitride chip substrate can be easily identified visually, the shape of the main plane of the group III nitride chip substrate is more preferably a rectangular shape among right-angled rectangles.

(Step of placing a group III nitride chip substrate)
Referring to FIG. 2, in the method for growing a group III nitride crystal of this embodiment, a plurality of group III nitride chip substrates 12 are arranged so that the normal directions of the main plane 12m of each group III nitride chip substrate 12 are Each side plane is so parallel that the <hk- (h + k) 0> directions (where h and k are integers) other than the <10-10> direction of each group III nitride chip substrate 12 are parallel to each other. 12s and 12t are disposed adjacent to each other.

  By disposing the plurality of group III nitride chip substrates 12 as described above, the normal line at an arbitrary position of the main plane 12m extends across the entire plurality of group III nitride chip substrates 12 arranged at the position < The inclination angle θ is 1.0 ° or less with respect to the 0001> direction, and all the side planes 12s and 12t are {hk− (h + k) 0} planes other than the {10−10} plane (where h and k is an integer). Therefore, the group III nitride crystal 20 having a high crystallinity and a flat crystal growth surface 20g can be grown on the main surface of the plurality of group III nitride chip substrates 12. Further, by arranging a large number of group III nitride chip substrates 12 as described above, a group III nitride crystal 20 having a large size, high crystallinity and a flat crystal growth surface 20g can be grown.

(Step of growing group III nitride crystal)
Referring to FIG. 2, the group III nitride crystal growth method of the present embodiment is a step of growing group III nitride crystal 20 on main plane 12 m of a plurality of arranged group III nitride chip substrates 12. And comprising.

  Through this process, the group III nitride crystal 20 is epitaxially grown on the main surface of the plurality of group III nitride chip substrates 12 while inheriting the crystallinity of the plurality of group III nitride chip substrates 12. Here, the normal line at an arbitrary position of the main plane 12m has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at the position over the plurality of group III nitride chip substrates 12. Therefore, the grown group III nitride crystal 20 has a normal at an arbitrary position of the virtual plane 20h cutting the vicinity of the crystal growth surface 20g parallel to the main plane 12m with respect to the <0001> direction at that position. The inclination angle θc (that is, the inclination angle θc formed between the normal line and the <0001> direction at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g parallel to the main plane 12m) is about 1.0 ° or less. High crystallinity.

  Here, the inclination angle θc between the normal line and the <0001> direction at an arbitrary position of the virtual plane 20h cutting the vicinity of the crystal growth surface 20g in parallel with the main plane 12m is the crystal growth surface 20g at the arbitrary position. It is synonymous with the inclination angle θc formed by the virtual plane 20h that cuts the vicinity parallel to the main plane 12m and the {0001} plane 20c, and is measured by the position of the X-ray diffraction peak with respect to the (0002) plane or the (0004) plane. be able to.

  Further, all the side planes 12s, 12t of the plurality of group III nitride chip substrates 12 are {hk- (h + k) 0} planes (where h and k are integers) other than the {10-10} plane. Therefore, facets are not formed on the crystal growth surface 20g of the group III nitride crystal 20, and it becomes flat.

  When a large number of group III nitride chip substrates 12 are arranged, a large group III nitride crystal 20 is obtained. In this way, a large group III nitride crystal 20 having high crystallinity and a flat crystal growth surface 20g is obtained.

Example 1
1. Step of Preparing Multiple Group III Nitride Chip Substrates (1) Production of Group III Nitride Mother Crystal Referring to FIG. 4, a GaN mother crystal that is a group III nitride mother crystal 10 was produced as follows. First, a mask layer is formed by sputtering on a main surface of a GaAs substrate having a diameter of 2 inches (50.8 mm) and a thickness of 0.8 mm as a different base substrate (not shown) having a main surface of (111) A plane. A SiO ₂ layer having a thickness of 100 nm was formed. Next, a pattern in which openings having a diameter of 2 μm were arranged in a hexagonal close-packed manner at a pitch of 4 μm in the SiO ₂ layer (mask layer) was formed by photolithography and etching. Here, the main plane of the GaAs substrate was exposed at each opening.

Next, a GaN low-temperature buffer layer having a thickness of 80 nm is grown at an ambient temperature of 500 ° C. by an HVPE method on a GaAs substrate on which a SiO ₂ layer (mask layer) having a plurality of openings in the main plane is formed. A GaN mother crystal (Group III nitride mother crystal 10) having a thickness of 5 mm was grown on the GaN low-temperature buffer layer.

  Next, by etching using aqua regia, the GaAs substrate (heterogeneous base substrate) is removed from the GaN mother crystal (group III nitride mother crystal 10), and the diameter is 2 inches (50.8 mm) and the thickness is 3 mm. A GaN mother crystal (Group III nitride mother crystal 10) was obtained.

  Such a GaN mother crystal (Group III nitride mother crystal 10) retains the warp that occurs during crystal growth. That is, in this GaN mother crystal (Group III nitride mother crystal 10), the {0001} face 10c is curved with the (0001) face being concave, and the curvature is 300 μm at the height difference and 1.0 m in the radius of curvature. Met.

  When a GaN substrate (Group III nitride substrate 11) having a diameter of 2 inches (50.8 mm) and a thickness of 0.4 mm is cut out from the GaN mother crystal (Group III nitride mother crystal), an arbitrary surface 11m of the GaN substrate is arbitrarily selected. The tilt angle that the normal line at the position has with respect to the <0001> direction at that position is about 1.5 °.

(2) Fabrication of Group III Nitride Chip Substrate With reference to FIGS. 1 and 4, from the GaN mother crystal (group III nitride mother crystal 10), all side planes 12s, 12t of the GaN chip substrate are {10-10. } A plurality of GaN chip substrates (Group III nitride chip substrate 12) were cut out so as not to include the surface. Each cut out GaN chip substrate was 5 mm × 10 mm × 800 μm thick. Specifically, in each GaN chip substrate (III-nitride chip substrate 12), a 5 mm × 10 mm main surface 12m is close to the (0001) plane, and a 5 mm × 800 μm side plane 12s is substantially (2-310). The side plane 12t of 10 mm × 800 μm was almost (−130) plane.

The crystallinity of the GaN mother crystal (Group III nitride mother crystal 10) is inherited as it is to each of the cut out GaN chip substrates (Group III nitride chip substrate 12). Accordingly, each GaN chip substrate (group III nitride chip substrate 12) having a main plane 12m of 5 mm × 10 mm is 0.15 ° or less in a direction parallel to the side of 5 mm with respect to the central inclination angle θ ₀ . It has a differential inclination angle θ ₁ of 0.3 ° or less in a direction parallel to a side of 10 mm. Here, the central inclination angle θ ₀ is defined as the inclination angle formed between the normal line and the <0001> direction at the center of the main plane 12 m of the group III nitride chip substrate 12. Further, the differential inclination angle θ ₁ is defined as an inclination angle formed by the <0001> direction at an arbitrary position of the main plane 12m and the <0001> direction at the center of the main plane 12m in each group III nitride chip substrate 12. To do.

  While adjusting the main surface 12m of each GaN substrate (group III nitride chip substrate 12) so that the normal at the center of the main surface 12m is the same as the <0001> direction, the average roughness of the main surface 12m is 5 nm. Then, it was polished and flattened.

  Next, while adjusting the side planes 12s and 12t of each GaN substrate (group III nitride chip substrate 12) to be perpendicular to the main plane 12m, the average roughness Ra of the side planes 12s and 12t is Polishing and flattening to 5 nm.

The central inclination angle θ ₀ of each GaN substrate (Group III nitride chip substrate 12) whose main plane and side plane have been flattened by polishing as described above is measured from the position of the X-ray diffraction peak with respect to the (0002) plane, 56 chip substrates having a central inclination angle θ ₀ of 0.2 ° or less were selected. That is, with respect to each selected GaN substrate (group III nitride chip substrate 12), the inclination angle θ formed by the normal at an arbitrary position of the main plane 12m and the <0001> direction at that position is θ = | θ _0. Since it is represented by + θ ₁ |, it was calculated to be 0.5 ° or less.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, 56 GaN chip substrates (Group III nitride chip substrate 12) selected as described above are arranged on the main plane 12m of each GaN chip substrate. The side planes 12s, so that the normal directions are parallel to each other, the <2-310> directions of the GaN chip substrates are parallel to each other, and the <-2130> directions of the GaN chip substrates are parallel to each other. 12 were arranged adjacent to each other, and the peripheral part was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 2, HVPE is formed on the main plane 12m of the circular substrate formed by arranging 56 GaN chip substrates (group III nitride chip substrate 12). GaN crystal (group III nitride crystal 20) is grown for about 3 hours at 1135 ° C. in an atmosphere of 10% by volume gallium chloride gas, 20% by volume ammonia gas and 70% by volume hydrogen gas. I let you.

An integrated GaN crystal having a flat crystal growth surface was obtained on the substrate. The dislocation density of such a GaN crystal is 1 × 10 ⁶ cm ^{− in} the crystal region immediately above the GaN chip substrate (group III nitride chip substrate 12) when non-light emitting dark spot density is measured by CL (cathode luminescence). ^2. It was 6 × 10 ⁶ cm ⁻² in the crystal region immediately above the joint portion of each side plane 12s, 12t of the GaN chip substrate (group III nitride chip substrate 12).

In addition, an inclination angle formed between a normal line at an arbitrary position of a virtual plane 20h that cuts the vicinity of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) in parallel with the main plane 12m and the <0001> direction at that position. θc was calculated as follows. From the measurement of the position of the X-ray diffraction peak with respect to the (0002) plane at four positions 20 mm away in the four directions perpendicular to each other from the center of the GaN crystal, the obtained GaN crystal has its central tilt angle θc _0. Was 0.2 ° or less, and the differential inclination angle θc ₁ was 0.4 ° or less. Here, the central inclination angle θc ₀ is an inclination formed between the normal line and the <0001> direction at the center of the virtual plane 20 h that cuts the vicinity of the crystal growth surface 20 g of the group III nitride crystal 20 in parallel to the main plane 12 m. It is defined as a corner. Further, the differential inclination angle θc ₁ means that in the group III nitride crystal 20, the <0001> direction at an arbitrary position of the virtual plane 20 h that cuts the vicinity of the crystal growth surface 20 g parallel to the main plane 12 m, and the crystal growth surface 20 g It is defined as an inclination angle formed with the <0001> direction at the center of the virtual plane 20h that cuts the vicinity in parallel to the main plane 12m. At this time, since the inclination angle θc is expressed by θc = | θc ₀ + θc ₁ |, it was calculated as 0.6 ° or less.

  Further, the half-value width of the X-ray diffraction peak in the rocking curve relating to the (0002) plane at the center of the crystal growth surface of the GaN crystal was as small as 80 arcsec and had high crystallinity. The results are summarized in Table 1.

(Example 2)
1. Step of preparing a plurality of group III nitride chip substrates Referring to FIGS. 1 and 2, a plurality of group III nitride chip substrates are prepared in the same manner as in Example 1 except that the average roughness Ra of each side plane 12s, 12t is 2.5 nm. GaN chip substrate (Group III nitride chip substrate 12) was prepared.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, in the same manner as in Example 1, 56 GaN chip substrates (Group III nitride chip substrate 12) are arranged, and the peripheral portion is arranged. This was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 2, the circular substrate formed by arranging 56 GaN chip substrates (group III nitride chip substrate 12) in the same manner as in Example 1. A GaN crystal (Group III nitride crystal 20) was grown on the main plane 12m.

A GaN crystal in which the crystal growth surface was flat and integrated on the substrate was obtained. The dislocation density of the GaN crystal is 1 × 10 ⁶ cm ^{−2 in} the crystal region immediately above the GaN chip substrate (Group III nitride chip substrate 12), and each side plane of the GaN chip substrate (Group III nitride chip substrate 12). It was 4 × 10 ⁶ cm ⁻² in the crystal region immediately above the junction portion of 12s and 12t. The obtained GaN crystal had a central inclination angle θc ₀ of 0.2 ° or less and a differential inclination angle θc ₁ of 0.3 ° or less. Therefore, the inclination angle between the normal line at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) in parallel with the main plane 12m and the <0001> direction at that position. θc was calculated to be 0.5 ° or less using θc = | θc ₀ + θc ₁ |. Further, the half-value width of the X-ray diffraction peak in the rocking curve relating to the (0002) plane at the center of the crystal growth surface of the GaN crystal was as small as 70 arcsec and had high crystallinity. The results are summarized in Table 1.

(Example 3)
1. Step of Preparing Multiple Group III Nitride Chip Substrates Referring to FIGS. 1 and 2, the normal line at the center of main plane 12m of each GaN chip substrate (Group III nitride chip substrate 12) and the <0001> direction are formed. A plurality of GaN chip substrates were prepared in the same manner as in Example 1 except that 56 chip substrates having a central inclination angle θ ₀ of 0.5 ° or less were selected. Similar to the GaN chip substrate of Example 1, such a GaN chip substrate is 0.15 ° or less in a direction parallel to the side of 5 mm with respect to the central inclination angle θ _{0 and} parallel to the side of 10 mm. The direction has a differential inclination angle θ ₁ of 0.3 ° or less. That is, for each selected GaN chip substrate (group III nitride chip substrate 12), the inclination angle θ between the normal line at an arbitrary position of the main plane 12m and the <0001> direction at that position is θ = | θ It was calculated as 0.8 ° or less using ₀ + θ ₁ |.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, in the same manner as in Example 1, 56 GaN chip substrates (Group III nitride chip substrate 12) are arranged, and the peripheral portion is arranged. This was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 2, the circular substrate formed by arranging 56 GaN chip substrates (group III nitride chip substrate 12) in the same manner as in Example 1. A GaN crystal (Group III nitride crystal 20) was grown on the main plane 12m.

A GaN crystal integrated on the substrate was obtained. The dislocation density of the GaN crystal is 1 × 10 ⁶ cm ^{−2 in} the crystal region immediately above the GaN chip substrate (Group III nitride chip substrate 12), and each side plane of the GaN chip substrate (Group III nitride chip substrate 12). It was 8 × 10 ⁶ cm ⁻² in the crystal region immediately above the junction portion of 12s and 12t. The obtained GaN crystal had a central tilt angle θc ₀ of 0.5 ° or less and a differential tilt angle θc ₁ of 0.5 ° or less. Therefore, the inclination angle between the normal line at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) in parallel with the main plane 12m and the <0001> direction at that position. θc was calculated to be 1.0 ° or less using θc = | θc ₀ + θc ₁ |. Further, the half-value width of the X-ray diffraction peak in the rocking curve with respect to the (0002) plane at the center of the crystal growth surface of the GaN crystal was as small as 120 arcsec and had high crystallinity. The results are summarized in Table 1.

(Comparative Example 1)
1. Step of preparing a plurality of group III nitride chip substrates Referring to FIGS. 1 and 2, the central tilt angle θ _{0 of} each GaN chip substrate (group III nitride chip substrate 12) is 1.2 ° or less. A plurality of GaN chip substrates were prepared in the same manner as in Example 1 except that the chip substrates were selected. Similar to the GaN chip substrate of Example 1, such a GaN chip substrate is 0.15 ° or less in a direction parallel to the side of 5 mm with respect to the central inclination angle θ _{0 and} parallel to the side of 10 mm. The direction has a differential inclination angle θ ₁ of 0.3 ° or less. That is, for each selected GaN chip substrate (group III nitride chip substrate 12), the inclination angle θ between the normal line at an arbitrary position of the main plane 12m and the <0001> direction at that position is θ = | θ It was calculated as 1.5 ° or less using ₀ + θ ₁ |.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, in the same manner as in Example 1, 56 GaN chip substrates (Group III nitride chip substrate 12) are arranged, and the peripheral portion is arranged. This was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 2, the circular substrate formed by arranging 56 GaN chip substrates (group III nitride chip substrate 12) in the same manner as in Example 1. A GaN crystal (Group III nitride crystal 20) was grown on the main plane 12m.

An integrated GaN crystal having a flat crystal growth surface on the substrate was obtained. The dislocation density of the GaN crystal is 1 × 10 ⁶ cm ^{−2 in} the crystal region immediately above the GaN chip substrate (Group III nitride chip substrate 12), and each side plane of the GaN chip substrate (Group III nitride chip substrate 12). It was 1 × 10 ⁷ cm ⁻² in the crystal region immediately above the 12s and 12t junctions. The obtained GaN crystal had a central tilt angle θc ₀ of 1.2 ° or less and a differential tilt angle θc ₁ of 0.3 ° or less. Therefore, the inclination angle between the normal line at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) in parallel with the main plane 12m and the <0001> direction at that position. θc was calculated to be 1.5 ° or less using θc = | θc ₀ + θc ₁ |. Moreover, the half width of the X-ray diffraction peak in the rocking curve with respect to the (0002) plane at the center of the GaN crystal was as large as 220 arcsec, and the crystallinity was low. Such a low crystalline GaN crystal degrades the characteristics of a semiconductor device using the GaN crystal as a substrate. The results are summarized in Table 1.

(Comparative Example 2)
1. Step of Preparing Multiple Group III Nitride Chip Substrates Referring to FIGS. 1 and 3, each GaN chip substrate (Group III nitride chip substrate 12) has a 5 mm × 800 μm side plane 12s (10-10) plane, 10 mm A plurality of GaN chip substrates were prepared in the same manner as in Example 1 except that the GaN chip substrate was cut out so that the side surface 12t of × 800 μm became the (11-20) plane. Similar to the GaN chip substrate of Example 1, such a GaN chip substrate has a central inclination angle θ ₀ of 0.2 ° or less, and is parallel to a side of 5 mm with respect to the central inclination angle θ ₀ . It has a differential inclination angle θ ₁ of 0.15 ° or less in the direction and 0.3 ° or less in the direction parallel to the side of 10 mm. That is, for each selected GaN chip substrate (group III nitride chip substrate 12), the inclination angle θ between the normal line at an arbitrary position of the main plane 12m and the <0001> direction at that position is θ = | θ It was calculated as 0.5 ° or less using ₀ + θ ₁ |.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 3, in the same manner as in Example 1, 56 GaN chip substrates (Group III nitride chip substrate 12) are arranged, and the peripheral portion is arranged. This was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 3, the circular substrate formed by arranging 56 GaN chip substrates (group III nitride chip substrate 12) in the same manner as in Example 1. A GaN crystal (Group III nitride crystal 20) was grown on the main plane 12m.

A GaN crystal integrated on the substrate was obtained. However, facets 20f extending in a direction parallel to the <11-20> direction at a pitch of 10 mm were formed on the crystal growth surface 20g of the GaN crystal. For this reason, the yield of GaN crystals decreased. After polishing the crystal growth surface 20g to form a flat surface parallel to the main plane 12m of the circular substrate, the dislocation density of the GaN crystal was measured by measuring the non-light emitting dark spot density by CL (cathode luminescence). The crystal region directly above the GaN chip substrate (Group III nitride chip substrate 12) was as low as 1 × 10 ⁶ cm ⁻² , but the side planes 12s and 12t of the GaN chip substrate (Group III nitride chip substrate 12) were low. In the crystal region immediately above the joint portion, it was as high as 2 × 10 ⁷ cm ⁻² .

  Here, regarding the GaN crystal (group III nitride crystal 20), the CL emission intensity of the crystal region immediately above the joint portion of each side plane 12s, 12t of the GaN chip substrate is the CL emission intensity of the crystal region immediately above the GaN chip substrate. Compared to the intensity, it was twice or more in the vicinity of 365 nm. From this, it is considered that the crystal region immediately above the joint portion of the GaN chip substrate has taken in more impurities than the crystal region directly above the GaN chip substrate.

Further, the obtained GaN crystal had a central tilt angle θc ₀ of 0.2 ° or less and a differential tilt angle θc ₁ of 0.3 ° or less. Therefore, the inclination angle θc formed by the normal line at any position of the plane parallel to the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) and the <0001> direction at that position is θc = | θc ₀ + θc. ₁ | was used to calculate 0.5 ° or less.

  Further, the half width of the X-ray diffraction peak in the rocking curve with respect to the (0002) plane at the center of the GaN crystal was as small as 80 arcsec, and the crystallinity was high. The results are summarized in Table 1.

Example 4
1. Step of Preparing Multiple Group III Nitride Chip Substrates Referring to FIGS. 1 and 2, a plurality of GaN chip substrates (Group III nitride chip substrate 12) were prepared in the same manner as in Example 1. In the GaN chip substrate, as in the GaN chip substrate of the first embodiment, the inclination angle θ between the normal line at an arbitrary position of the main plane 12m and the <0001> direction at that position is 0.5 ° or less (here Θ = | θ ₀ + θ ₁ |, the central inclination angle θ ₀ is 0.2 ° or less, and the differential inclination angle θ ₁ is 0.3 ° or less.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, in the same manner as in Example 1, 56 GaN chip substrates (Group III nitride chip substrate 12) are arranged, and the peripheral portion is arranged. This was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal Referring to FIG. 2, on the main plane 12m of the circular substrate formed by arranging 56 GaN chip substrates (Group III nitride chip substrate 12), III A GaN crystal (Group III nitride crystal 20) was grown by a solution method using a solution in which nitrogen was dissolved in a Group element melt.

  Specifically, the circular substrate was placed in a carbon crucible having an inner diameter of 80 mm with its main plane 12 m facing upward, and 100 g of metal Ga was placed thereon. The crucible in which the circular substrate and the metal Ga are arranged is held in a nitrogen gas atmosphere at an atmospheric temperature of 1150 ° C. and an atmospheric pressure of 2000 atm (202.7 MPa) for 30 hours, thereby forming a Ga melt in which the metal Ga is melted. A solution in which nitrogen was dissolved was brought into contact with the main plane 12m of the circular substrate to grow a GaN crystal (group III nitride crystal 20) on the main plane 12m.

A GaN crystal having a thickness of 20 μm and a flat crystal growth surface integrated on the circular substrate was obtained. The dislocation density of the GaN crystal is 1 × 10 ⁶ cm ^{−2 in} the crystal region immediately above the GaN chip substrate (Group III nitride chip substrate 12), and each side plane of the GaN chip substrate (Group III nitride chip substrate 12). It was 3 × 10 ⁶ cm ⁻² in the crystal region immediately above the junction portion of 12s and 12t. Further, the obtained GaN crystal had a central tilt angle θc ₀ of 0.2 ° or less and a differential tilt angle θc ₁ of 0.3 ° or less. Accordingly, θc = | θc ₀ + θc ₁ | is used as the inclination angle θc between the normal line at an arbitrary position of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) and the <0001> direction at that position. And calculated to be 0.5 ° or less. Further, the half-value width of the X-ray diffraction peak in the rocking curve related to the (0002) plane at the center of the GaN crystal was as small as 80 arcsec and had high crystallinity. The results are summarized in Table 1.

(Example 5)
1. Step of Preparing Multiple Group III Nitride Chip Substrates (1) Production of Group III Nitride Mother Crystal With reference to FIG. 4, an AlN mother crystal that is a group III nitride mother crystal 10 was produced as follows. First, an AlN mother crystal is formed on a main plane of a SiC substrate having a diameter of 2 inches (50.8 mm) and a thickness of 0.5 mm having a main plane of (0001) as a different base substrate (not shown) by a sublimation method. (Group III nitride mother crystal 10) was grown.

In the growth of the AlN mother crystal by the sublimation method, until the crystal grows to a thickness of 0.5 mm, the atmospheric temperature is set to 1700 ° C., and 0.1% by volume of carbon dioxide (CO ₂ ) gas is supplied. The crystal was doped with carbon (C) atoms. Thereafter, the atmospheric temperature was set to 1800 ° C., supply of carbon dioxide gas was stopped, and an AlN mother crystal having a thickness of 5 mm was further grown. On the crystal growth surface (corresponding to the (0001) plane) of the grown AlN mother crystal, a plurality of hexagonal pyramidal recesses formed by a plurality of facets were formed.

  Next, the SiC substrate was removed from the AlN mother crystal (Group III nitride mother crystal 10) by mechanical polishing to obtain an AlN mother crystal having a diameter of 2 inches (50.8 mm) and a thickness of 3 mm. At this time, the crystal region of 0.5 mm thickness doped with AlN carbon atoms in the AlN mother crystal was removed together with the SiC substrate.

  Next, the crystal growth surface (approximately (0001) plane) and the opposite surface (approximately (000-1) plane) of the AlN mother crystal were polished and planarized so that the average roughness Ra was 50 nm. Here, the average roughness Ra was measured by AFM. In this way, an AlN mother crystal (Group III nitride mother crystal 10) having a thickness of 3 mm having a principal surface that is substantially (0001) and a principal surface that is substantially (000-1) is obtained.

(2) Production of Group III Nitride Chip Substrate From AlN mother crystal (Group III nitride mother crystal 10), a plurality of side planes 12s, 12t of the AlN chip substrate are not included in the {10-10} plane. An AlN chip substrate (Group III nitride chip substrate 12) was cut out. Each of the cut AlN chip substrates was 5 mm × 10 mm × 800 μm thick. In each AlN chip substrate (group III nitride chip substrate 12), the main surface 12m of 5 mm × 10 mm is approximately (0001) plane, the side plane 12s of 5 mm × 800 μm is approximately (2-310) plane, and the side of 10 mm × 800 μm The plane 12t was approximately (-2-130) plane.

Here, cut-out AlN chip substrate (III-nitride chip substrate 12), (0002) was measured the position of the X-ray diffraction peaks for surface, the central angle of inclination theta ₀ for 5mm sides The differential tilt angle θ ₁ was 0.1 ° or less in the parallel direction and 0.2 ° or less in the direction parallel to the side of 10 mm.

  Next, the average roughness of the main surface 12m is adjusted while adjusting the main surface 12m of each AlN substrate (Group III nitride chip substrate 12) so that the normal line at the center of the main surface 12m is the same as the <0001> direction. The surface was polished and flattened to a thickness of 5 nm. Next, while adjusting the side planes 12s and 12t of each AlN substrate (group III nitride chip substrate 12) to be perpendicular to the main plane 12m, the average roughness Ra of the side planes 12s and 12t is Polishing and flattening to 5 nm.

The central inclination angle θ ₀ of each AlN substrate (Group III nitride chip substrate 12) whose main plane and side plane have been flattened by polishing as described above is measured from the position of the X-ray diffraction peak with respect to the (0002) plane, 56 chip substrates having a central inclination angle θ ₀ of 0.5 ° or less were selected. That is, each selected AlN substrate (group III nitride chip substrate 12) has an inclination angle θ between a normal line at an arbitrary position of the main plane 12m and a <0001> direction at that position, θ = | θ ₀ Since it was represented by + θ ₁ |, it was calculated to be 0.7 ° or less.

2. Step of Arranging Multiple Group III Nitride Chip Substrates Referring to FIG. 2, 56 AlN chip substrates (Group III nitride chip substrate 12) selected as described above are arranged on a main plane 12m of each AlN chip substrate. The side planes 12s, so that the normal directions are parallel to each other, the <2-310> directions of the GaN chip substrates are parallel to each other, and the <-2130> directions of the AlN chip substrates are parallel to each other. 12t was placed adjacent to each other, and the peripheral part was removed to obtain a circular substrate having a diameter of 2 inches.

3. Step of Growing Group III Nitride Crystal With reference to FIG. 2, sublimation is performed on the main plane 12m of the circular substrate formed by arranging 56 AlN chip substrates (group III nitride chip substrate 12). By the method, an AlN crystal (Group III nitride crystal 20) was grown for 30 hours at an atmospheric pressure of 45 KPa and an atmospheric temperature of 2100 ° C. Thus, an AlN crystal having a flat integrated crystal growth surface 20 g having a thickness of about 3 mm and a diameter of 2 inches (50.8 mm) was obtained on the circular substrate.

The dislocation density of the AlN crystal was measured using a TEM (transmission electron microscope), and found to be 1 × 10 ⁶ cm ^{−2 in} the crystal region immediately above the AlN chip substrate (Group III nitride chip substrate 12). It was 6 × 10 ⁶ cm ⁻² in the crystal region immediately above the junction between the side planes 12 s and 12 t of the substrate (Group III nitride chip substrate 12).

The obtained AlN crystal had a central inclination angle θc ₀ of 0.5 ° or less and a differential inclination angle θc ₁ of 0.5 ° or less. Therefore, the inclination angle between the normal line at an arbitrary position of the virtual plane 20h that cuts the vicinity of the crystal growth surface 20g of the GaN crystal (group III nitride crystal 20) in parallel with the main plane 12m and the <0001> direction at that position. θc was calculated to be 1.0 ° or less using θc = | θc ₀ + θc ₁ |.

  The half width of the X-ray diffraction peak in the rocking curve with respect to the (0002) plane at the center of the AlN crystal was as small as 80 arcsec, and this AlN crystal had high crystallinity. The results are summarized in Table 1.

  Referring to Table 1, as shown in Examples 1 to 5, the normal line at an arbitrary position of main plane 12m has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at that position. A plurality of group III nitride chip substrates 12 in which the side planes 12s and 12t are {hk- (h + k) 0} planes (where h and k are integers) other than the {10-10} plane are prepared. The plurality of group III nitride chip substrates 12 are arranged such that the normal directions of the side planes 12s and 12t of each group III nitride chip substrate 12 are parallel to each other and the <10-10> direction of each group III nitride chip substrate 12 The side planes 12s and 12t are arranged adjacent to each other so that the other <hk- (h + k) 0> directions (where h and k are integers) are parallel to each other. I on the main plane 12 m of the group nitride chip substrate 12 By growing the group II nitride crystal 20, a large group III nitride crystal 20 having high crystallinity and a flat crystal growth surface was obtained (see FIG. 2).

  Further, referring to Examples 1 and 2, the group III nitride chip is reduced by reducing the average roughness Ra of the side planes 12s and 12t of the group III nitride chip substrate 12 from 5 nm or less to 2.5 nm or less. A normal line at an arbitrary position of a virtual plane 20h that cuts the vicinity of the crystal growth surface 20g in parallel with the main plane 12m and reduces the dislocation density in the crystal region immediately above the junction between the side planes 12s and 12t of the substrate 12. The tilt angle θc formed with the <0001> direction at the position was reduced, and the half-value width of the X-ray diffraction peak was reduced, so that a group III nitride crystal 20 with higher crystallinity was obtained (see FIG. 2).

  On the other hand, referring to Comparative Example 2, if any side plane of the group III nitride chip substrate is a {10-10} plane, an integrated group III nitride crystal 20 is obtained, but the crystal growth surface Since the recess due to the facet 20f was formed in 20g, the yield of the group III nitride crystal 20 was lowered (see FIG. 3). Further, in the group III nitride crystal 20, the dislocation density in the crystal region immediately above the junction between the side planes 12s and 12t of the group III nitride chip substrate 12 is increased.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10 Group III nitride mother crystal, 10c, 11c, 12c, 20c {0001} plane, 10g, 20g crystal growth surface, 11 Group III nitride substrate, 11m, 12m main plane, 12 Group III nitride chip substrate, 12s, 12t side plane, 20 group III nitride crystal, 20f facet, 20fc facet growth crystal region, 20h virtual plane.

Claims (3)

A group III nitride chip substrate having a main plane and a plurality of side planes,
A normal line at an arbitrary position of the main plane has an inclination angle θ of 1.0 ° or less with respect to the <0001> direction at the position, and each side plane has a {hk− other than {10−10} plane. Preparing a plurality of group III nitride chip substrates having a (h + k) 0 plane (where h and k are integers);
A plurality of the group III nitride chip substrates are arranged such that the normal directions of the main planes of the group III nitride chip substrates are parallel to each other and other than the <10-10> direction of the group III nitride chip substrates < arranging the side planes adjacent to each other so that hk- (h + k) 0> directions (where h and k are integers) are parallel to each other;
Growing a group III nitride crystal on the main plane of the plurality of group III nitride chip substrates arranged. A method for growing a group III nitride crystal.   The group III nitride crystal growth method according to claim 1, wherein an average roughness Ra of each of the side planes is 5 nm or less.   The method for growing a group III nitride crystal according to claim 1 or 2, wherein the main plane is rectangular.

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