JP5509680B2 - Group III nitride crystal and method for producing the same - Google Patents

Description

The present invention relates to a method for producing a group III nitride crystal, and relates to a method for producing a large-area group III nitride crystal having a principal surface with an arbitrarily specified plane orientation other than the (0001) plane.

Nitride semiconductors typified by gallium nitride have a large band gap, and the transition between bands is a direct transition type. Therefore, light emitting diodes such as ultraviolet, blue and green, semiconductor lasers and the like on the relatively short wavelength side It is a promising material as a substrate for semiconductor devices such as light-emitting elements and electronic devices.
The most common nitride semiconductor substrate at present is a substrate having a (0001) plane as a main surface (the main surface here means the surface on which a device is to be formed or the widest surface in the structure). . However, InGaN-based blue and green LEDs and LDs using a GaN substrate with the (0001) plane as the main surface have a problem that a piezoelectric field is generated in the [0001] axis direction, which is the growth axis. The piezo electric field is generated because the crystal structure of the InGaN layer is distorted and piezoelectric polarization occurs, and this polarization separates the holes and electrons injected into the light emitting layer, reducing the recombination probability contributing to light emission. For this reason, internal quantum efficiency becomes low and it leads to the fall of the external quantum efficiency of a light emitting device. InGaN blue, green LEDs and LDs with nonpolar planes such as {11-20} plane and {10-10} plane perpendicular to the (0001) plane of the GaN crystal as growth planes in order to weaken the influence of the piezoelectric field. Research is becoming active (see Non-Patent Document 1).

  Nitride semiconductors have a high melting point, and the dissociation pressure of nitrogen near the melting point is high, so that bulk growth from the melt is difficult. On the other hand, it is known that a nitride semiconductor substrate can be manufactured by using a vapor phase growth method such as a hydride vapor phase growth method (HVPE method) or a metal organic chemical vapor deposition method (MOCVD method). At this time, the nitride semiconductor crystal grown on the base substrate 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 be taken out by separating it from the support together with the substrate and removing the base substrate by a method such as polishing if necessary. (For example, refer to Patent Document 1).

  Kanbara et al., A plurality of nitride semiconductor bars, (0001) faces of adjacent nitride semiconductor bars, (000-1) faces, or (0001) faces and (000-1) faces face each other. The {10-10} planes of the nitride semiconductor bars are arranged so as to be the upper surface, and the nitride semiconductor is regrown on the upper surfaces of the arranged nitride semiconductor bars, so that the continuous {10-10} planes are mainly formed. A nitride semiconductor layer is formed on the surface to obtain a {10-10} plane nitride semiconductor wafer having a large area (see Patent Document 2).

  Mizuhara et al. Prepared a plurality of nitride semiconductor bars, the main surfaces of the plurality of nitride semiconductor bars were parallel to each other, and the [0001] directions of the bars were the same in the lateral direction. The substrates are arranged adjacent to each other, and a nitride semiconductor layer having a continuous {10-10} plane as a main surface is formed by regrowth of the nitride semiconductor on the upper surface of the arranged nitride semiconductor bars, and nitriding A semiconductor wafer has been obtained (see Patent Document 3).

JP 2006-240988 A JP 2006-315947 A JP 2008-143772 A

Nikkei Electronics 2006.8.14 P65-P70

  When a plate-like nitride semiconductor substrate having a desired main surface is manufactured by the method of Patent Document 1, the following problems may be encountered. For example, when trying to manufacture a relatively large plate-like nitride semiconductor substrate having a nonpolar surface as a main surface, there is no nitride semiconductor substrate having a relatively large nonpolar surface as a main surface as a base substrate. 1-102) A nonpolar surface is grown as a growth surface on a different kind of base substrate such as a plane sapphire substrate or {10-10} plane SiC substrate, and the base substrate is separated to obtain a substrate, or once of the base substrate After a crystal is grown on a polar face in a direction perpendicular to the polar face, it must be sliced to cut out the desired nonpolar face. In the former case, because of the growth on the different base substrate, many stacking defects enter the crystal, and a high-quality crystal cannot be obtained. In the latter case, a high-quality crystal having no stacking fault can be obtained, but it is extremely difficult to grow a thick crystal, and there is a limit to obtain a desired nitride semiconductor crystal by this method.

In the method of obtaining a large-area nonpolar plane substrate by arranging and re-growing a plurality of bars as in Patent Document 2 and Patent Document 3, the crystal crystal in the region above the boundary region between the seeds Deterioration is a problem.
In Patent Document 2, a step portion is formed at a junction between nitride semiconductor seeds by inclining the surface normal direction of the nitride semiconductor seed with respect to the {10-10} plane, and the step portion is formed in the nitride semiconductor layer. As a growth nucleus for regrowth, the crystallinity of the regrowth layer at the junction is improved. However, if only the surface normal direction of the nitride semiconductor seed is tilted with respect to the {10-10} plane for the purpose of providing a step at the junction, the parallelism between the front surface and the back surface is deteriorated, and processing such as polishing becomes difficult. Problems arise. In addition, a method is shown in which a ridge portion where a junction surface and a regrowth surface of a nitride semiconductor seed intersect is chamfered to form a growth nucleus for regrowth in the junction portion. According to this method, a V-shaped groove is formed on the junction, and the growth of the nitride semiconductor layer in the V-shaped groove becomes facet growth, and the dislocation generated at the junction forms a loop and disappears, reducing the dislocation density. It is supposed to let you. However, in reality, it is very difficult to chamfer such a small area. In addition, after chamfering, the seed is not fixed properly during the polishing process, and the seed moves, resulting in a problem that polishing cannot be performed well.

  Further, in Patent Document 3, as a measure for improving the crystallinity on the joint, the seeds are adjacent to each other in order to reduce the gap between the seeds. However, it is difficult to completely eliminate the gap at the atomic level. According to Patent Document 3, as a result, the threading dislocation density in the upper region of the junction is higher than that in the region directly above the seed.

The present invention solves the above-described problem of deterioration of crystallinity on the joint, and has a high crystallinity large area group III nitride crystal having a principal surface with an arbitrarily specified plane orientation other than the (0001) plane With the objective of providing a manufacturing method for the above, intensive studies were conducted. As a result, it has been found that crystal dislocations in the region above the boundary region between the seeds drastically decrease, and the present invention has been achieved. The present invention provides a plurality of seeds having an off angle;
Arranging the seed so that the main surface of the seed faces substantially in the same direction;
Growing a group III nitride crystal on the main surface of the seed;
A method for producing a group III nitride crystal containing
In the arranging step, the plurality of seeds are arranged so that the off-angle directions thereof are substantially the same direction.
That is, the following present invention has been provided as means for solving the problems.
[1] preparing a plurality of seeds having an off angle;
Arranging the seed so that the main surface of the seed faces substantially in the same direction;
Growing a group III nitride crystal on the main surface of the seed;
A method for producing a group III nitride crystal containing
The method for producing a group III nitride crystal, wherein in the arranging step, the plurality of seeds are arranged so that the off-angle directions are substantially the same.
[2] The method for producing a group III nitride crystal according to [1], wherein an absolute value of the off-angle is in a range of 0.1 ° to 15 °.
[3] The seed according to [1] and [2], wherein the seed has a main surface and a back surface.
A method for producing a group nitride crystal.
[4] The method for producing a group III nitride crystal according to [1] to [3], wherein the seed has a bonding surface and the bonding surfaces are arranged to face each other.
[5] The method for producing a group III nitride crystal as described in [1] to [4], wherein a plane orientation of the main surface of the seed is a plane other than the (0001) plane.
[6] The method for producing a group III nitride crystal as described in [1] to [5], wherein a plane orientation of the main surface of the seed is a {10-10} plane.
[7] The method for producing a group III nitride crystal as described in [1] to [6], wherein a plane orientation of the main surface of the seed is a {11-20} plane.
[8] A group III nitride crystal produced using the production method described in any one of [1] to [7].
[9] The group III nitride crystal according to [8], having a plane orientation other than the (0001) plane.
[10] A group III nitride crystal produced using the production method described in [8],
A group III nitride crystal, wherein a decrease in band edge PL intensity in a region above a boundary region between the seeds is 60% or less with respect to a band edge PL intensity in a region above the seed.
[11] A group III nitride crystal produced using the production method described in [8],
A group III nitride crystal, wherein an increase in dislocation density in a region above a boundary region between the seeds is 5 times or less of a dislocation density in a region above the seed.
[12] A group III nitride crystal produced by the production method according to any one of claims 1 to 7,
A light emitting device or an electronic device having a wavelength of 350 to 600 nm, wherein the group III nitride crystal according to any one of claims 8 to 11 is used.

  According to the method for producing a nitride semiconductor crystal of the present invention, it is possible to efficiently produce a large-area nitride semiconductor crystal having a principal surface with an arbitrarily specified plane orientation other than the (0001) plane by a simple method. it can. A nitride semiconductor crystal in which the threading dislocation density in the region above the boundary region between the seeds is kept low can be easily manufactured.

HVPE equipment m-plane GaN free-standing substrate setting method (Examples 1, 5, 6) Example of m-plane GaN free-standing substrate setting method (Example 2) m-plane GaN free-standing substrate setting method (Example 3, Comparative Example 1) Example of m-plane GaN free-standing substrate setting method (Example 4) Junction trace Schematic diagram for explaining off angle

  Below, the manufacturing method of the nitride semiconductor crystal of this invention is demonstrated in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the following description, a gallium nitride crystal may be described as an example of the nitride semiconductor crystal, but the nitride semiconductor crystal that can be employed in the present invention is not limited to this. 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.

(Seed material, lattice constant, thermal expansion coefficient)
The seed is not particularly limited as long as a desired nitride semiconductor crystal can be grown on the crystal growth surface. It may be used as a base substrate for crystal growth. For example, sapphire, SiC, ZnO, and a group III nitride semiconductor can be mentioned. Preferably, a seed of a nitride semiconductor that is the same as or different from the nitride semiconductor to be manufactured is used, and more preferably, the same type as the group III element that constitutes the nitride semiconductor to be manufactured. It is a case where a seed of a nitride semiconductor containing at least a group III element is used,
More preferably, a nitride semiconductor seed of the same type as the nitride semiconductor to be manufactured is used. From another viewpoint, it is preferable to select a seed having a lattice constant close to that of the nitride semiconductor crystal to be manufactured and having a small difference in thermal expansion coefficient.

(Seed shape)
The seed shape is not particularly limited as long as it does not depart from the essence of the present invention, but a so-called bar shape may be used. In addition, it is preferable that a plurality of seeds have the same shape because it is easy to arrange a large number of seeds. The shape of the main surface of the seed may be a polygon, and a rectangle or a square can also be preferably used. If the length of one side of the main surface of the seed is short, more seeds must be prepared when manufacturing a large-area nitride semiconductor substrate. Therefore, the length of one side of the main surface of the seed is preferably 5 mm or more, more preferably 15 mm or more, and further preferably 20 mm or more. The use of a large seed is preferable because the orientation accuracy of the arranged seed can be improved and the number of seed joint surfaces that tend to cause a decrease in crystallinity can be reduced.

(Seed orientation)
In crystal geometry, a display such as (hkl) or (hkil) is used to indicate the plane orientation of a crystal plane. The plane orientation of the crystal plane in a hexagonal crystal such as a group III nitride crystal is represented by (hkil). Here, h, k, i and l are integers called Miller indices and have a relationship of i = − (h + k). The plane having the plane orientation (hkil) is referred to as the (hkil) plane. The {hkil} plane means a generic plane orientation including the (hkil) plane and individual plane orientations equivalent to the crystal geometry.

  The surface orientation of the seed main surface is not particularly limited as long as it is other than the (0001) plane, and is nonpolar such as a polar surface of (000-1) plane, {1-100} plane, {11-20} plane, etc. Examples thereof include semipolar planes such as planes, {1-102} planes, and {11-22} planes. When the seed shape is rectangular, the seed main surface is a {10-10} plane or a {11-20} plane, and the plane orientations of the four side surfaces are (0001) plane, (000-1) plane, {11-20 } Plane, {11-20} plane, or (0001) plane, (000-1) plane, {10-10} plane, {10-10} plane, and the seed main surface is {10-10 }, The plane orientation of the four side surfaces is more preferably (0001) plane, (000-1) plane, {11-20} plane, {11-20} plane.

(Seed main surface area)
If the area of the main surface of the seed is small, more seeds must be prepared, and the number of bonding surfaces also increases, which may increase the twist angle distribution in the nitride semiconductor crystal grown on the seed. Increase. Therefore, the better the area of the seed of the main surface is large, preferably at 50 mm ² or more, more preferably 75 mm ² or more, more preferably 100 mm ² or more.

(An angle between the joint surface and the main surface)
The angle formed by the joint surface and the main surface is not particularly limited, but it is preferable that the angle is substantially a right angle in consideration of ease of seed preparation. The angle formed by the joint surface and the main surface is preferably 88 ° to 92 °, more preferably 89 ° to 91 °, and even more preferably 89.5 ° to 90.5 °.
(Off angle expression method)
FIG. 7 is a schematic diagram showing the relationship between the main surface normal direction of the seed and the direction of the seed crystal axis direction for explaining the inclination (off angle) of the main surface normal direction with respect to the low index surface. . Here, it is assumed that the low index surface of the main surface is the (10-10) surface and the bonding surfaces are the (0001) surface and the (11-20) surface. An angle formed between the seed main surface normal direction and the [10-10] axis is φ, and a projection axis is obtained by projecting the seed main surface normal onto a plane defined by the [10-10] axis and the [0001] axis. The angle formed with the [10-10] axis is φc, the projection main axis is projected onto a plane defined by the [10-10] axis and the [11-20] axis of the seed crystal axis, and [10 −10] The angle made with the axis is φa. In this case, the main surface normal direction of the seed is inclined by φc in the [0001] direction and by φa in the [11-20] direction with respect to the low index surface of the main surface, that is, the (10-10) surface. It can be expressed as Here, the [hkil] direction refers to a direction perpendicular to the (hkil) plane (the normal direction of the (hkil) plane), and the <hkil> direction refers to the [hkil] direction and its crystal geometry. A generic direction including individual directions equivalent to.

(Off-angle and crystal growth on seed)
If the seed main surface normal direction coincides with the orientation of the low index surface, the growth of each seed surface in the normal direction becomes dominant. In this case, laterally grown portions from adjacent seeds meet at the gap at the joint. As in the ELO meeting part, a large amount of dislocations occur in the meeting part on the gap. A low index surface tilted from the main surface is generated by properly growing the main surface normal direction with respect to the low index surface (off angle). This surface grows obliquely with respect to the main surface while maintaining a low index surface. When the off-angle is attached to the normal direction of the joint surface, the joint grows diagonally from one seed and reaches the next seed. By causing association on the adjacent seed, a large amount of dislocations can be suppressed. When the off-angle is small, the laterally growing parts from both adjacent sides meet on the gap before the low index surface growing part of one seed straddles the gap. Therefore, the lower limit of the absolute value of the seed off angle is preferably 0.1 ° or more, more preferably 1 ° or more, and further preferably 3 ° or more. On the other hand, when the off-angle is large, the surface step density becomes high, so that there is a problem that step bunching (step coarsening) is likely to occur during growth. Therefore, the upper limit of the absolute value of the off angle is preferably 15 ° or less, more preferably 10 ° or less, and further preferably 7 ° or less.

Further, when the off-angle distribution between seeds is small, the tilt angle distribution of the crystal after bonding can be reduced. The off-angle distribution between the seeds is preferably within 1 °, more preferably within 0.7 °, and more preferably within 0.5 °.
Here, the low index plane means that when the plane orientation is expressed by a Miller index (hklm), the absolute value of each index is 2 or less (| h | ≦ 2, | k | ≦ 2, | l | ≦ 2, | M | ≦ 2) and the sum of the absolute values of the indices is 6 or less (| h | + | k | + | l | + | m | ≦ 6). For example, when a seed having a hexagonal crystal structure is used as the base crystal substrate, the (1-100) plane and the crystallographically equivalent plane, (11-20) plane and the crystal thereof are used as the low index plane. And a (1-102) plane and a crystallographically equivalent plane.

(Inclination with respect to the low index surface in the normal direction of the joint surface)
The normal direction of the joint surface may be inclined from the low index surface or may not be inclined. However, considering the ease of placement and the twist angle distribution of the crystal after bonding, it is desirable that the difference in inclination from the low index surface in the axial direction between the two facing bonding surfaces is smaller. For example, the bonding surface opposite to the bonding surface whose normal direction is + 5 ° in the [11-20] direction and + 5 ° in the [10-10] direction is inclined from the (0001) plane is the [11-20] direction. It is desirable to use a joint surface in which the normal direction of the + 5 ° joint surface in the [10-10] direction is inclined from the (000-1) plane. Therefore, the difference in inclination from the low index surface in the axial direction between the two facing joint surfaces is preferably within 1 °, more preferably within 0.7 °, and more preferably within 0.5 °.

Further, when the absolute value distribution of the inclination from the low index surface in each axial direction between the seeds is small, the twist angle distribution of the crystal after bonding can be reduced by facing the bonding surfaces almost in parallel. The absolute value distribution of the inclination from the low index plane in the direction of each axis between the seeds is preferably within 1 °, more preferably within 0.7 °, and more preferably within 0.5 °.
(Cut out main surface, cut out method)
A seed having a desired surface can be obtained by cutting a crystal as necessary. For example, a group III nitride semiconductor substrate having a (0001) plane is formed, and then a {10-10} plane or a {11-20} plane is cut out so that a {10-10} plane or {11- A seed having a 20} plane as a principal plane can be obtained. As a cutting method, there are a method of grinding (grinding, cutting) with a scissors, grinder, inner peripheral slicer, wire saw, etc., a method of polishing by polishing, a method of dividing by cleavage, etc., but {10-10} by cleavage It is preferable to form a plane or a {11-20} plane. As for the cleavage method, a diamond scriber may be used for cutting and a laser scriber device may be used. You may divide by hand as it is, and you may carry out with the braking device on other foundations.

The parallelism of the front and back surfaces of the seed is preferably within 1 °, more preferably within 0.7 °, and even more preferably within 0.5 °. When the parallelism of the seeds deteriorates, there arises a problem that processing such as polishing becomes difficult.
(manufacturing device)
In the present invention, a plate-like crystal is grown in a direction perpendicular to the crystal growth surface of the seed by supplying a source gas to the seed. Examples of the growth method include a metal organic chemical deposition method (MOCVD method), a hydride vapor deposition method (HVPE method), and the like, but the HVPE method having a high growth rate is preferable.

  FIG. 1 is a diagram for explaining a configuration example of a nitride semiconductor crystal manufacturing apparatus used in the present invention, but there is no particular limitation on the details of the configuration. The HVPE apparatus shown in FIG. 1 includes, in a reactor 100, a susceptor 108 for placing a seed and a reservoir 106 for storing a nitride semiconductor material to be grown. 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.

(Reactor material, atmospheric gas type)
As a 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.

(Susceptor material, shape, distance from growth surface to susceptor)
Carbon is preferable as the material of the susceptor 108, and a material whose surface is coated with SiC is more preferable. The shape of the susceptor 108 is not particularly limited as long as the seed used in the present invention can be installed, but it is preferable that no structure exists near the crystal growth surface when the crystal is grown. 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.

(Reservoir)
The reservoir 106 contains a nitride semiconductor material to be grown. For example, when a group III-V nitride semiconductor is grown, a raw material to be a group III source is added. 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,
3 can supply HCl gas. 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.

(Nitrogen source (ammonia), separate gas, dopant gas)
From the introduction pipe 104, a source 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.

(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.

(Exhaust pipe location)
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.
(Crystal growth conditions)
Crystal growth in the present invention is usually performed at 950 ° C. to 1120 ° C., preferably at 970 ° C. to 1100 ° C., more preferably at 980 ° C. to 1090 ° C., and further at 990 ° C. to 1080 ° C. preferable. 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.

(Crystal growth rate)
The growth rate of crystal growth in the present invention varies depending on the growth method, growth temperature, raw material gas supply amount, crystal growth plane orientation, etc., but is generally in the range of 5 μm / h to 500 μm / h, and is 10 μm / h or more. Is preferably 50 μm / h or more, and more 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.

(Nitride semiconductor crystal area)
According to the present invention, a nitride semiconductor crystal having a large main surface area can be easily obtained. The area of the main surface can be appropriately adjusted according to the size of the crystal growth surface of the seed and the crystal growth time. According to the present invention, for example, the area of the main surface can be 500 mm ² or more, 2500 mm ² or more, and further 10000 mm ² or more.

(Types of nitride semiconductor crystals)
The type of nitride semiconductor crystal provided by the present invention is not particularly limited. Specific examples include Group III nitride semiconductor crystals, and more specific examples include gallium nitride, aluminum nitride, indium nitride, or mixed crystals thereof.
(Use of nitride semiconductor crystals)
The nitride semiconductor crystal obtained 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 having relatively short wavelengths such as semiconductor lasers, and electronic devices. It is also possible to obtain a larger nitride semiconductor crystal by using the 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.

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of −5 ° in the [0001] direction and 0 ° in the [11-20] direction Two (10-10) plane GaN free-standing substrate seeds having The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
The (0001) plane and the (000-1) plane were selected as the bonding plane. As shown in FIG. 2, two seeds are arranged in two rows in the [0001] direction so that the cross section of the (0001) plane and the cross section of the (000-1) plane face each other, and the cross sections are within 0.5 °. The susceptor was arranged on the susceptor so as to be parallel, the temperature of the reaction chamber was increased to 1020 ° C., and a GaN single crystal film was grown for 40 hours. In this single crystal growth step, 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 NH3 gas G4 is 7.05 × 10 ³ Pa. did.

  After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is combined, and the outer periphery of the arranged seed is in the [11-20] direction. Each was expanded by 2 mm in the [-1-120] direction, 2 mm in the [0001] direction, and 2 mm in the [000-1] direction. It grew 3.5 mm in the [10-10] direction. After the outer shape processing and surface polishing treatment, three rectangular (10-10) plane free-standing substrates of 29 mm in the [11-20] direction, 10 mm in the [0001] direction, and 330 μm thick were produced by general slicing and polishing. .

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed. As a result of PL mapping measurement using a He—Cd laser with a central wavelength of 325 nm as an excitation light source and a laser output of 1 mW and a laser beam diameter of 100 μm, the wavelength of the crystal in the region above the boundary region between the seeds is 366 nm. The band edge emission intensity was 84% of the emission intensity in the region above the seed (hereinafter referred to as the PL intensity ratio to the region above the boundary region between the seed and the region above the seed).

As a result of performing CL measurement in an acceleration voltage of 3 kV, a magnification of 3000 times, and a 100 um square region, an average dark spot density (hereinafter referred to as between seed and seed) where the region above the boundary region between the seed and the center is included. The CL measurement of the region above the boundary region was 5.3 × 10 ⁶ cm ⁻² , which was 1.8 times the average dark spot density of the region above the seed. The half width of the X-ray rocking curve in the region above the seed was 43 seconds in (10-10) plane symmetry reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, has an off angle of 0 ° in the [0001] direction and + 5 ° in the [11-20] direction. Two (10-10) plane GaN free-standing substrate seeds were prepared. The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
As the bonding surface, (11-20) plane and (-1-120) plane were selected. As shown in FIG. 3, two seeds are arranged in one row in the [0001] direction, two rows in the [11-20] direction, so that the cross section of the (11-20) plane and the cross section of the (-1-120) plane face each other. In addition, they were arranged on the susceptor so that the cross sections had a parallelism within 0.5 °. Other conditions were grown under the same conditions as in Example 1.

  After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is combined, and the outer periphery of the arranged seed is in the [11-20] direction. Each was expanded by 2 mm in the [-1-120] direction, 2 mm in the [0001] direction, and 2 mm in the [000-1] direction. It grew 3.5 mm in the [10-10] direction. After the outer shape processing and the surface polishing treatment, three rectangular m-plane free-standing substrates having a thickness of 54 mm in the [11-20] direction, 7 mm in the [0001] direction and a thickness of 330 μm were produced by general slicing and polishing.

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed.
The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 56%.
The average dark spot density in the CL measurement of the region above the boundary region between the seeds is 8.7 × 10 ⁶ cm ⁻² 2.9 times the average dark spot density of the region above the seed. there were.

  The half width of the X-ray rocking curve in the region above the seed was 44 seconds in (10-10) plane-symmetric reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of −5 ° in the [0001] direction and + 5 ° in the [11-20] direction Four (10-10) plane GaN free-standing substrate seeds were prepared. The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
The (0001) plane, (000-1) plane, (11-20) plane, and (-1-120) plane were selected as the bonding plane. As shown in FIG. 4, the four seeds are arranged in two rows of [0001] direction, two rows of [11-20] direction, so that the cross section of the (0001) plane and the cross section of the (000-1) plane face each other. They were arranged on the susceptor so that the cross section of the (11-20) plane and the cross section of the (-1-120) plane face each other, and the cross sections had a parallelism within 0.5 °. Other conditions were grown under the same conditions as in Example 1.

  After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is combined, and the outer periphery of the arrayed seed is in the [11-20] direction. Each was expanded by 2 mm in the [-1-120] direction, 2 mm in the [0001] direction, and 2 mm in the [000-1] direction. It grew 3.5 mm in the [10-10] direction. After the outer shape processing and surface polishing treatment, three rectangular m-plane free-standing substrates having a thickness of 54 mm in the [11-20] direction, 10 mm in the [0001] direction, and a thickness of 330 μm were produced by general slicing and polishing.

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed.
The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 66%.
The average dark spot density in the CL measurement in the region above the boundary region between the seeds was 2.4 times.

  The half width of the X-ray rocking curve in the region above the seed was 43 seconds in (10-10) plane symmetry reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

A rectangular parallelepiped having a length of 25 mm in the [10-10] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of −5 ° in the [0001] direction and + 5 ° in the [11-20] direction Four (10-10) plane GaN free-standing substrate seeds were prepared. The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
The (0001) plane, (000-1) plane, (10-10) plane, and (-1010) plane were selected as the bonding plane. As shown in FIG. 5, four seeds are arranged in two rows of [0001] direction, two rows of [10-10] direction, the cross section of (0001) plane and the cross section of (000-1) plane face each other, and The cross sections of the (10-10) plane and the (-1010) plane were arranged on the susceptor so that the cross sections had a parallelism within 0.5 °. Other conditions were grown under the same conditions as in Example 1.

  After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is bonded, and the outer periphery of the arranged seed is in the [10-10] direction. The [-1010] direction was enlarged by 2 mm, the [0001] direction was increased by 2 mm, and the [000-1] direction was increased by 2 mm. It grew 3.5 mm in the [11-20] direction. After the outer shape processing and surface polishing treatment, three rectangular m-plane free-standing substrates having a thickness of 54 mm in the [10-10] direction, 10 mm in the [0001] direction, and a thickness of 330 μm were produced by general slicing and polishing.

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed.
The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 71%.
The average dark spot density in the CL measurement of the region above the boundary region between the seeds is 6.2 × 10 ⁶ cm ^−2, which is 2.3 times the average dark spot density of the region above the seed. there were.

  The half width of the X-ray rocking curve in the region above the seed was 42 seconds in (10-10) plane symmetry reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of −2 ° in the [0001] direction and 0 ° in the [11-20] direction Two (10-10) plane GaN free-standing substrate seeds having The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
The (0001) plane and the (000-1) plane were selected as the bonding plane. As shown in FIG. 2, two seeds are arranged in two rows in the [0001] direction so that the cross section of the (0001) plane and the cross section of the (000-1) plane face each other, and the cross sections are within 0.5 °. It arranged on the susceptor so that it might become parallelism. Other conditions were grown under the same conditions as in Example 1.

  After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is combined, and the outer periphery of the arranged seed is in the [11-20] direction. Each was expanded by 2 mm in the [-1-120] direction, 2 mm in the [0001] direction, and 2 mm in the [000-1] direction. It grew 3.5 mm in the [10-10] direction. After the outer shape processing and surface polishing treatment, three rectangular m-plane free-standing substrates having a thickness of 29 mm in the [11-20] direction, 10 mm in the [0001] direction, and a thickness of 330 μm were produced by general slicing and polishing.

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed.
The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 42%.
The average dark spot density in CL measurement of the region above the boundary region between the seeds was 1.6 × 10 ⁷ cm ⁻² , which was 3.9 times the average dark spot density of the region above the seed. It was.

  The half width of the X-ray rocking curve in the region above the seed was 47 seconds in (10-10) plane-symmetric reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of −9 ° in the [0001] direction and 0 ° in the [11-20] direction Two (10-10) plane GaN free-standing substrate seeds having The parallelism of the front and back surfaces of the seed m surface is within 0.5 °.
The (0001) plane and the (000-1) plane were selected as the bonding plane. As shown in FIG. 2, two seeds are arranged in two rows in the [0001] direction so that the cross section of the (0001) plane and the cross section of the (000-1) plane face each other, and the cross sections are within 0.5 °. It arranged on the susceptor so that it might become parallelism. Other conditions were grown under the same conditions as in Example 1.
After the single crystal growth step is completed, the temperature is lowered to room temperature, and the grown crystal is taken out. The region above the boundary region between the seeds is combined, and the outer periphery of the arranged seed is in the [11-20] direction. Each was expanded by 2 mm in the [-1-120] direction, 2 mm in the [0001] direction, and 2 mm in the [000-1] direction. It grew 3.5 mm in the [10-10] direction. After the outer shape processing and surface polishing treatment, three rectangular m-plane free-standing substrates having a thickness of 29 mm in the [11-20] direction, 10 mm in the [0001] direction, and a thickness of 330 μm were produced by general slicing and polishing.

Crystals in the region above the boundary region between the seeds were observed with a differential interference optical microscope at a magnification of 50 to 1000 times, but no unusual pattern such as a streak was observed.
The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 89%.
The average dark spot density in the CL measurement in the region above the boundary region between the seeds was 7.7 × 10 ⁶ cm ⁻² , which was 1.5 times the average dark spot density in the other regions. .

The full width at half maximum of the X-ray rocking curve in the region above the seed was 113 seconds in (10-10) plane symmetry reflection when the X-ray beam was incident perpendicularly to the [0001] direction.
[Comparative Example 1]

A rectangular parallelepiped having a length of 25 mm in the [11-20] direction and 3 mm in the [0001] direction and having a thickness of 330 μm, an off angle of 0 ° in the [0001] direction and 0 ° in the [11-20] direction Four (10-10) plane GaN free-standing substrate seeds were prepared. Thereafter, single crystal growth, slicing and polishing were performed under the same conditions as in Example 3.
When the crystals on the joint were observed with a differential interference optical microscope at a magnification of 50 to 1000, streaks were confirmed on the joint.

The PL intensity ratio for the region above the boundary region between the seeds and the region above the seeds was 29%.
The average dark spot density in the CL measurement of the region above the boundary region between the seeds was 2.7 × 10 ⁷ cm ⁻² , which was 5.6 times the average dark spot density of the other regions. It was.
The half width of the X-ray rocking curve in the region above the seed was 58 seconds in (10-10) plane symmetry reflection when the X-ray beam was incident perpendicularly to the [0001] direction.

Group III nitride crystals manufactured by the manufacturing method according to the present invention include light emitting elements (light emitting diodes, laser diodes, etc.), electronic devices (rectifiers, bipolar transistors, field effect transistors, or HEMTs (High Electron Mobility Transistors)). ), 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.

100 reactor 101 carrier gas pipe 102 dopant gas pipe 103 group III raw material pipe 104 group V raw material pipe 105 HCl gas pipe 106 group III raw material reservoir 107 heater 108 susceptor 109 exhaust pipe G1 carrier gas G2 dopant gas G3 III Group gas G4 Group V gas G5 HCl gas

Claims (8)

A plurality of seeds having a each of which is a surface forming the main face and the main surface and the angle joint surface, so as to face the main surface the same direction, so as to joint faces between adjacent seed faces An arrangement process to arrange ,
A step of growing a GaN crystal on the main surface of the plurality of seeds arranged in the arrangement step ;
Only including,
Each of the plurality of seeds is a (10-10) plane GaN free-standing substrate having an off angle in the [0001] direction in the range of −9 ° to −2 °.
The off-angle distribution between the plurality of seeds is within 0.5 °,
In the disposing step, the plurality of seed, manufacturing method of a GaN crystal which adjacent even between two seed [0001] direction, characterized in that arranged so as to face the same direction. The manufacturing method according to claim 1, wherein the parallelism of the front and back surfaces is within 0.5 ° in all of the plurality of seeds. The manufacturing method according to claim 1 or 2, wherein an off angle in the [0001] direction is the same and an off angle in the [11-20] direction is the same among all of the plurality of seeds. The manufacturing method according to claim 3, wherein an off angle in the [11-20] direction is 0 ° in all of the plurality of seeds. The manufacturing method as described in any one of Claims 1-4 whose angle which the said main surface and a joining surface make is 88 degrees-92 degrees. The manufacturing according to any one of claims 1 to 5, wherein the plurality of seeds includes a seed having a bonding surface on the [0001] direction side and a seed having a bonding surface on the [000-1] direction side. Method. The manufacturing method of a GaN substrate which has the process of manufacturing a GaN crystal using the manufacturing method as described in any one of Claims 1-6, and the process of processing the GaN crystal obtained by this process into a board | substrate. A method for manufacturing a semiconductor device, comprising: a step of manufacturing a GaN substrate using the manufacturing method according to claim 7; and a step of manufacturing a semiconductor device using the GaN substrate obtained in the step.

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