TW202015104A - Method for manufacturing semipolar free-standing substrate - Google Patents

Abstract

The present invention provides a method for producing a semi-polar self-supporting substrate, in which a preparation step (S10) wherein a semi-polar seed substrate that is composed of a group III nitride semiconductor is prepared, said seed substrate having a semi-polar surface as a main surface, a group III nitride semiconductor layer formation step (S20) wherein a group III nitride semiconductor layer is formed by epitaxially growing a group III nitride semiconductor on the semi-polar seed substrate, a cut-out step (S30) wherein a semi-polar self-supporting substrate, which has the semi-polar surface as a main surface, is cut out from the group III nitride semiconductor layer, and a processing step (S40) wherein all the remaining group III nitride semiconductor layer is removed from the semi-polar seed substrate on which a part of the group III nitride semiconductor layer remains are performed, and subsequently the group III nitride semiconductor layer formation step and the cut-out step are performed, while reusing the semi-polar seed substrate.

Description

Method for manufacturing semi-polar independent substrate

The invention relates to a method for manufacturing a semi-polar independent substrate.

Patent Document 1 discloses a technique for growing a thick GaN crystal film on a base substrate having a sapphire substrate and a GaN crystal thin film with high density of pores, and then peeling off the thick GaN crystal film After removing the GaN crystal film, this step is performed using a sapphire substrate.

Patent Literature 2 discloses a technique for growing a nitride semiconductor epitaxial layer on a nitride semiconductor substrate, separating the nitride semiconductor epitaxial layer from the nitride semiconductor substrate, and thereafter, the nitride The semiconductor substrate is subjected to surface treatment, and then the surface-treated nitride semiconductor substrate is used to perform this step.

In Patent Document 3, there is disclosed a technique in which a nitride semiconductor layer is formed on a base substrate obtained by joining rectangular crystal sheets containing a nitride semiconductor, and the nitride semiconductor layer is separated from the base substrate, and thereafter , And then use the base substrate to perform this step.

Patent Document 4 discloses a technique in which after implanting ions near the surface of a nitride semiconductor substrate, a silicon substrate is bonded to the nitride semiconductor substrate by heat treatment, and nitrogen is implanted with the ion-implanted layer as a boundary Most of the compound semiconductor substrate is peeled off from the silicon substrate, and then, this step is performed using the nitride semiconductor substrate obtained by removing the ion-implanted layer.

Patent Literature 5 discloses a technique in which a plurality of nitride semiconductor layers constituting an element are stacked on a nitride semiconductor substrate to form an upper layer portion, and then the upper layer portion is separated from the nitride semiconductor substrate. After that, this step is performed again using a nitride semiconductor substrate.

Patent Documents 6 and 7 disclose a method of forming a group III nitride semiconductor layer with a semipolar surface as a main surface on a sapphire substrate. Prior technical literature Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2012-158497 Patent Document 2: Japanese Patent Laid-Open No. 2014-166953 Patent Document 3: Japanese Patent Laid-Open No. 2015-187043 Patent Document 4: Japanese Patent Laid-Open No. 2006-210660 Patent Literature 5: Japanese Patent Laid-Open No. 2007-73569 Patent Literature 6: Japanese Patent No. 6266742 Patent Document 7: Japanese Patent No. 6232150

[Problems to be solved by the invention]

The inventors of the present invention have studied the technique of forming a group III nitride semiconductor layer on a seed substrate including a group III nitride semiconductor, and then separating the group III nitride semiconductor layer from the seed substrate to obtain an independent substrate, Afterwards, this step was performed using the seed substrate on which the group III nitride semiconductor layer was separated, and as a result, the following problems were found.

The details are shown by the following examples. In the above technique, when a group III nitride semiconductor layer is formed on the seed substrate by c-plane growth, holes or cracks are easily generated on the surface of the group III nitride semiconductor layer . As a result, holes or cracks are easily generated on the surface of the obtained independent substrate. Patent documents 1 to 7 do not disclose the problem and its solution.

The object of the present invention is to improve the surface condition of the obtained independent substrate by forming a group III nitride semiconductor layer on a seed substrate containing a group III nitride semiconductor and then applying a group III nitride semiconductor The layers are separated from the seed substrate to obtain an independent substrate, and then this step is performed using the seed substrate that has separated the group III nitride semiconductor layer. [Technical means to solve the problem]

According to the invention, Provided is a manufacturing method of a semipolar independent substrate, which performs: a preparation step, which is to prepare a semipolar seed substrate with a semipolar surface as a main surface and containing a group III nitride semiconductor; A step of forming a group III nitride semiconductor layer, which is to epitaxially grow a group III nitride semiconductor on the above semi-polar seed substrate to form a group III nitride semiconductor layer; A cutting step, which is to cut a semipolar independent substrate with a semipolar plane as its main surface from the above-mentioned group III nitride semiconductor layer; and The processing step is to remove all the group III nitride semiconductor layer from the semi-polar seed substrate remaining a part of the group III nitride semiconductor layer after the cutting step; and then use the group III nitride to remove The semi-polar seed crystal substrate after the semiconductor layer is subjected to the group III nitride semiconductor layer forming step and the cutting step. [Effect of invention]

According to the present invention, the surface state of the independent substrate obtained in the following technique is formed by forming a group III nitride semiconductor layer on a seed substrate including a group III nitride semiconductor and then applying the group III nitride semiconductor The layers are separated from the seed substrate to obtain an independent substrate, and then this step is performed using the seed substrate that has separated the group III nitride semiconductor layer.

Hereinafter, an embodiment of the method for manufacturing a semipolar independent substrate of the present invention will be described using drawings. In addition, the drawings are only schematic diagrams for explaining the structure of the invention, and the size, shape, number, and ratio of the sizes of the various members are not limited to the drawings.

<First Embodiment> "Overall situation and overview" The flowchart of FIG. 1 shows an example of the processing flow of the manufacturing method of the semipolar independent substrate of this embodiment. As shown in the figure, in the manufacturing method of the semipolar independent substrate of this embodiment, the preparation step S10, the group III nitride semiconductor layer forming step S20, the cutting step S30, and the processing step S40 are sequentially performed.

Here, the outline of each step will be described using the step diagram of FIG. 2.

In the preparation step S10, as shown in FIG. 2(1), a semipolar seed substrate 1 including a group III nitride semiconductor with a semipolar surface as the main surface is prepared.

In the group III nitride semiconductor layer forming step S20, as shown in FIG. 2(2), the group III nitride semiconductor is epitaxially grown on the semipolar seed substrate 1 to form the group III nitride semiconductor layer 2.

In the cutting step S30, as shown in FIG. 2(3), a part of the group III nitride semiconductor layer 2 (the separation part 2-2 of the group III nitride semiconductor layer) is separated from the semipolar seed substrate 1, and A semipolar independent substrate with a semipolar surface as the main surface was obtained. Furthermore, a plurality of semi-polar independent substrates may be obtained by slicing the separation portion 2-2 of the group III nitride semiconductor layer.

In the processing step S40, the semi-polar seed substrate 1 in which a part of the group III nitride semiconductor layer 2 (the remaining portion 2-1 of the group III nitride semiconductor layer) remains is processed to remove the group III nitride semiconductor layer残残部2-1 2-1.

Thereafter, using the semipolar seed substrate 1 after removing the remaining portion 2-1 of the group III nitride semiconductor layer, the group III nitride semiconductor layer forming step S20 and the cutting step S30 are performed. Furthermore, the processing step S40 may be further performed to reuse the semipolar seed substrate 1 a plurality of times.

Next, each step will be described in detail.

"Preparation Step S10" In the preparation step S10, as shown in FIG. 2(1), a semipolar seed substrate 1 including a group III nitride semiconductor with a semipolar surface as the main surface is prepared. The main surface of the semi-polar seed crystal substrate 1 can be exemplified by the {-1-12-3} plane, the plane with a deviation angle of less than 15° from the {-1-12-3} plane, the {-1-12-4} plane And {-1-12-2}, etc., but not limited to these.

In the preparation step S10, the semipolar seed substrate 1 is manufactured by performing the process shown in the flowchart of FIG. As shown in FIG. 3, in the preparation step S10, the fixing step S11, the first growth step S12, the cooling step S13, the second growth step S14, and the seed substrate cutting step S15 are sequentially performed.

In the fixing step S11, the base substrate is fixed to the base. For example, as shown in FIG. 4(2), the base 20 to which the base substrate 10 shown in FIG. 4(1) is fixed is fixed.

The base substrate 10 includes a group III nitride semiconductor layer 12 having a semipolar surface as a main surface. The group III nitride semiconductor layer 12 is, for example, a GaN layer.

The semi-polar plane is a plane other than the polar plane and the non-polar plane. The main surface of the III-nitride semiconductor layer 12 (the exposed surface in the figure) may be a semi-polar surface on the +c side (semi-polar surface on the Ga polar side: expressed by the Miller index (hkml), and a semi-polarity where l is greater than 0 Surface), or a semi-polar surface on the -c side (semi-polar surface on the N-polar side: expressed by the Miller index (hkml), and a semi-polar surface with l not reaching 0).

The base substrate 10 may be a laminate including layers other than the group III nitride semiconductor layer 12, or may be a single layer of only the group III nitride semiconductor layer 12. As an example of the layered body, for example, a layered body in which the sapphire substrate 11, the buffer layer (omitted in the figure) and the group III nitride semiconductor layer 12 are sequentially stacked as shown in FIG. 4(1) can be exemplified, however, it is not limited Here. For example, the sapphire substrate 11 may be replaced with another heterogeneous substrate. In addition, a buffer layer may not be included. In addition, other layers may be included.

The manufacturing method of the base substrate 10 is not particularly limited, and all techniques can be used. For example, a group III nitride semiconductor may be epitaxially grown by a MOCVD (metal organic chemical vapor deposition, organic metal chemical vapor deposition) method on a sapphire substrate 11 that has a specific surface orientation. Group III nitride semiconductor layer 12. In this case, by adjusting the following conditions and the like to form a group III nitride semiconductor layer 12 having a desired semipolar plane whose main surface becomes either the N polar side or the Ga polar side, the above conditions refer to The orientation of the main surface of the sapphire substrate 11, the presence or absence of nitriding treatment when the sapphire substrate 11 before the buffer layer is heat-treated, the growth conditions when forming the buffer layer, the growth conditions when forming the group III nitride semiconductor layer 12, When a metal-containing gas (eg, trimethyl aluminum, triethyl aluminum) is supplied to the main surface of the sapphire substrate 11 to form a metal film and a metal carbide film, or when forming a buffer layer or a group III nitride semiconductor layer 12 Growth conditions. The details are disclosed in Patent Documents 6 and 7.

As another example of the manufacturing method of the base substrate 10, a group III nitride semiconductor layer obtained by growing on the c-plane can be processed (eg, slicing, etc.) to obtain a group III nitrogen having the desired semipolar plane as the main surface Compound semiconductor layer (base substrate 10).

The maximum diameter of the group III nitride semiconductor layer 12 is, for example, Φ50 mm or more and Φ6 inches or less. The thickness of the group III nitride semiconductor layer 12 is, for example, 50 nm or more and 1 mm or less. The diameter of the sapphire substrate 11 is, for example, Φ50 mm or more and Φ6 inches or less. The thickness of the sapphire substrate 11 is, for example, 100 μm or more and 10 mm or less.

Next, the base 20 will be described. The susceptor 20 has characteristics such as not to be deformed due to the stress of the warped base substrate 10 caused by the heating in the first growth step S12 or the second growth step S14. As an example of such a susceptor 20, a carbon susceptor, a silicon carbide coated carbon susceptor, a boron nitride coated carbon susceptor, a quartz susceptor, etc. may be exemplified, but it is not limited thereto.

Next, a method of fixing the base substrate 10 to the base 20 will be described. In this embodiment, as shown in FIG. 4(2), the back surface of the base substrate 10 (the back surface of the sapphire substrate 11) is fixed to the surface of the base 20. With this, the deformation of the base substrate 10 is suppressed. As a fixing method, a method that does not cause peeling due to the heating in the first growth step S12 or the second growth step S14 or the warping force of the base substrate 10 that may be warped by the heating is required. For example, a method of fixing using an alumina-based, carbon-based, zirconia-based, silica-based, or nitride-based adhesive can be exemplified.

Returning to FIG. 3, in the first growth step S12, as shown in FIG. 4(3), with the base substrate 10 fixed to the susceptor 20, the main surface of the group III nitride semiconductor layer 12 is used The HVPE (Hydride Vapor Phase Epitaxy) method grows group III nitride semiconductors. With this, the first growth layer 30 including the single crystal group III nitride semiconductor is formed. For example, GaN is epitaxially grown under the following growth conditions to form a GaN layer (first growth layer 30).

Growth temperature: 900℃～1100℃ Growth time: 1 h～50 h V/III ratio: 1～20 Growth film thickness: 100 μm～10 mm

In the first growth step S12, a polycrystalline group III nitride semiconductor is formed along the side surface of the laminate including the susceptor 20, the base substrate 10, and the first growth layer 30. The polycrystalline group III nitride semiconductor is attached to all or most of the side surfaces of the above-mentioned laminate. The attached polycrystalline group III nitride semiconductor is connected to each other to form a ring. Then, the above-mentioned laminate is held inside the ring-shaped polycrystalline group III nitride semiconductor.

In addition, in the first growth step S12, in addition to the side surface of the above-mentioned laminated body, a polycrystalline group III nitride semiconductor may be formed on the back surface of the susceptor 20. The polycrystalline group III nitride semiconductor is attached to all or most of the side surface of the above-mentioned layered body and the back surface of the base 20. The attached polycrystalline group III nitride semiconductor is connected to each other to form a cup shape. Then, the above laminate is held inside the cup-shaped polycrystalline group III nitride semiconductor.

Returning to FIG. 3, in the cooling step S13, the laminate including the susceptor 20, the base substrate 10, and the first growth layer 30 is cooled. The purpose of the cooling here is to use the strain (stress) generated by the difference in the linear expansion coefficients of the first growth layer 30 and the sapphire substrate 11 to crack the first growth layer 30, thereby relaxing the stress. It is desirable to relax the stress before the second growth step S14. As long as the purpose can be achieved, the method of cooling is not particularly limited. For example, after the first growth step S12, the layered product may be taken out of the HVPE device and cooled to room temperature.

As shown in FIG. 4(3), the first growth layer 30 after the cooling step S13 has cracks (cracks, cracks, etc.) 31. As shown, the crack 31 may exist on the surface of the first growth layer 30. Furthermore, the crack 31 may be generated during the first growth step S12 or may be generated during the cooling step S13.

Returning to FIG. 3, in the second growth step S14, as shown in FIG. 4(4), with the base substrate 10 fixed to the susceptor 20, the HVPE method is used on the first growth layer 30. Group III nitride semiconductor growth. With this, the second growth layer 40 including the single crystal III-nitride semiconductor is formed. For example, GaN is epitaxially grown under the following growth conditions to form a GaN layer (second growth layer 40). The growth conditions for forming the first growth layer 30 and the growth conditions for forming the second growth layer 40 may be the same or different.

Growth temperature: 900℃～1100℃ Growth time: 1 h～50 h V/III ratio: 1～20 Growth film thickness: 100 μm～10 mm

In the second growth step S14, the second growth layer 40 is formed on the first growth layer 30 with the ring-shaped polycrystalline group III nitride semiconductor formed in the first growth step S12 remaining. The purpose of the remaining ring-shaped polycrystalline group III nitride semiconductor is to suppress the separation by retaining the first growth layer 30 that may be separated into a plurality of parts by cracks 31 from the outer periphery. If the first growth layer 30 is separated into a plurality of parts, the plane orientation of each of the plurality of parts will shift, or the handling and workability will deteriorate. In addition, there is a possibility that the original shape cannot be reproduced due to the disappearance or crushing of some parts. According to this embodiment, since the surface orientation deviation or separation can be suppressed, this defect can be suppressed.

Furthermore, all of the polycrystalline group III nitride semiconductor formed in the first growth step S12 may remain as it is, as long as the above purpose can be achieved, and the polycrystalline formed in the first growth step S12 may not necessarily remain All of the III-nitride semiconductors. That is, a part of the polycrystalline group III nitride semiconductor can be removed.

In the second growth step S14, a polycrystalline group III nitride semiconductor is also formed. The polycrystalline group III nitride semiconductor can be formed along the side surface of the laminate including the base 20, the base substrate 10, the first growth layer 30, and the second growth layer 40 or the back surface of the base 20.

In the second growth step S14, on the surface of the first growth layer 30 where the crack 31 is present, a group III nitride semiconductor is grown by the HVPE method to form the second growth layer 40. In this case, the growth surface (the surface of the first growth layer 30) is not continuous at the crack 31 portion. Group III nitride semiconductors grown from each of the first surface region and the second surface region separated from each other with the crack 31 as a boundary are grown and bonded to each other and integrated.

Returning to FIG. 3, in the seed crystal substrate cutting step S15, at least a part of the second growth layer 40 is cut out as the semi-polar seed crystal substrate 1.

For example, as shown in FIG. 4(5), a laminate including the susceptor 20, the base substrate 10, the first growth layer 30, and the second growth layer 40 is sliced, and at least a portion of the second growth layer 40 is removed from the susceptor 20 is separated to make a semi-polar seed substrate 1. Furthermore, at least a part of the second growth layer 40 separated from the susceptor 20 may be sliced to obtain a plurality of semipolar seed crystal substrates 1. In addition to slicing, at least a part of the second growth layer 40 may be separated from the susceptor 20 by methods such as grinding, grinding, burning, decomposition, and dissolution.

According to the above, the semipolar seed substrate 1 including the group III nitride semiconductor with the semipolar plane as the main surface can be obtained.

According to this preparation step S10, the semiconductor epitaxial growth can be performed on the stress-relieved first growth layer 30 to form the second growth layer 40 (second growth step S14). Thus, compared to the case where the first growth layer 30 is thickened to the same thickness without easing the stress, the second growth layer 40 is less likely to have cracks or cracks.

Thus, according to this preparation step S10, a thick group III nitride semiconductor film having a semipolar surface as the main surface and a sufficient pore diameter can be grown. As a result, a bulk crystal including the first growth layer 30 and the second growth layer 40 is obtained. For example, the film thickness of the second growth layer 40 is 500 μm or more and 20 mm or less, and the maximum pore diameter is Φ50 mm or more and Φ6 inches or less. In addition, the film thickness of the first growth layer 30 is 100 μm or more and 10 mm or less. When the first growth layer 30 and the second growth layer 40 are combined, the film thickness becomes 600 μm or more and 30 mm or less. The surface of the second growth layer 40 has irregularities, and there are m-plane facets.

According to the preparation step S10 that can produce a bulk crystal with a sufficient pore diameter and a sufficient film thickness as described above, by cutting a part (Group III nitride semiconductor layer) from the bulk crystal, a half-crystal can be efficiently manufactured The semipolar seed substrate 1 having a polar surface as a main surface and a sufficient pore diameter and thickness. For example, the maximum diameter of the semipolar seed substrate 1 is Φ50 mm or more and Φ6 inches or less, and the thickness of the semipolar seed substrate 1 is 100 μm or more and 10 mm or less.

In addition, when the stress is relaxed, the first growth layer 30 has cracks 31. Moreover, the second growth layer 40 grown on the first growth layer 30 is grown by each of the first surface area and the second surface area of the first growth layer 30 separated from each other by the crack 31 as a boundary The crystals are joined together to form. Here, misalignment may occur at the interface between the first surface area and the second surface area. Furthermore, if the plane orientation of the first surface area and the second surface area shift, the misalignment on the interface increases. In this embodiment, the first growth layer 30 is held from the outer periphery by the ring-shaped polycrystalline group III nitride semiconductor. Thereby, the deviation of the above-mentioned plane orientation can be suppressed. As a result, the increase in the misalignment on the above interface can be suppressed.

Moreover, according to the preparation step S10 in which the first growth step S12 and the cooling step S13 are performed with the base 20 constrained to the base substrate 10, compared to the case where the same processing is performed without the constraint, it can be reduced to The number of cracks 31 generated in the first growth layer 30.

In addition, according to the case where the preparation step S10 of the second growth step S14 is performed in a state where the laminate including the base substrate 10 and the first growth layer 30 is constrained by the susceptor 20, the same processing is performed as in the state without the constraint In contrast, the number of cracks generated in the first growth layer 30 or the second growth layer 40 can be reduced, and separation can be suppressed.

In addition, according to this preparation step S10, as shown in FIGS. 5(1) and (2), the semipolar seed substrate 1 including the first portion 51 including the single crystal and the second portion 52 including the polycrystal can be manufactured. 5 (1) and (2) are plan views of the semi-polar seed substrate 1 and show the main surface.

The second part 52 is attached to the outer periphery of the first part 51. The second portion 52 has a ring shape, and holds the first portion 51 inside. The second part 52 may be maintained in a randomly attached state as shown in FIG. 5(1), or may be aligned by grinding or grinding as shown in FIG. 5(2).

According to such a semi-polar seed substrate 1 of this embodiment, the diameter can be obtained by the second portion 52. As a result, the handling or workability can be improved, and when the semi-polar seed crystal substrate 1 is used as the seed crystal substrate, the growth area of the first portion 51 including the single crystal can be ensured to be large. For example, the maximum diameter of the first portion 51 is Φ50 mm or more and Φ6 inches or less, and the maximum diameter of the group III nitride semiconductor layer having the first portion 51 and the second portion 52 is Φ51 mm or more and Φ6.5 inches or less.

In addition, the second portion 52 including polycrystals can be removed to obtain a semi-polar seed substrate 1 composed only of the first portion 51 including single crystals.

In addition, according to this preparation step S10 of the present embodiment, as shown in FIGS. 6 and 7, a semipolar seed substrate 1 including a plurality of portions having crystal axes different from each other is manufactured. 7 is a cross-sectional view of AA' of FIG. 6. Each of the illustrated area A and area B is a portion grown from each of the first surface area and the second surface area of the first growth layer 30 separated from each other by the crack 31 as a boundary.

The crystals in the regions A and B are different from each other due to the shift of the crystal axis between the first surface region and the second surface region of the first growth layer 30 (the shift caused by the crack 31). The direction Y of the crystal axis of the region A and the direction Z of the crystal axis of the region B in the figure indicate the directions of the same crystal axis. This feature is a feature that appears in the semi-polar seed substrate 1 manufactured in the preparation step. Furthermore, as described above, in the present embodiment, the existence of the ring-shaped polycrystalline group III nitride semiconductor holding the first growth layer 30 from the outer periphery can suppress the deviation of the plane orientation. As a result, the angle formed by the direction Y of the crystal axis of the region A and the direction Z of the crystal axis of the region B can be suppressed to 2° or less.

In addition, in the preparation step S10, the semi-polar seed crystal substrate 1 may also be manufactured by a process different from the process shown in the flowchart of FIG. For example, in the preparation step S10, the bulk crystal of the III-nitride semiconductor grown on the c-plane can be sliced so that the sliced surface becomes a semipolar surface to manufacture the semipolar seed substrate 1.

"Group III nitride semiconductor layer formation step S20" Returning to FIG. 1, in the group III nitride semiconductor layer forming step S20, as shown in FIG. 2(2), the group III nitride semiconductor is epitaxially grown on the semi-polar seed substrate 1 to form a group III nitrogen化物 Semiconductor layer 2. For example, a group III nitride semiconductor layer (eg, GaN) is grown on the main surface of the semipolar seed substrate 1 by the HVPE method to form a group III nitride semiconductor layer 2. The growth conditions are as follows.

Growth temperature: 900℃～1100℃ Growth time: 1 h～50 h V/III ratio: 1～20 Growth film thickness: 100 μm～20 mm

"Cut step S30" Returning to FIG. 1, in the cutting step S30, the semipolar independent substrate with the semipolar plane as the main surface is cut from the group III nitride semiconductor layer 2.

For example, in the cutting step S30, as shown in FIG. 2(3), the laminate including the semipolar seed substrate 1 and the group III nitride semiconductor layer 2 is sliced, and the group III nitride semiconductor layer 2 is sliced. A part (the separation part 2-2 of the group III nitride semiconductor layer) is separated from the semipolar seed substrate 1, whereby a semipolar independent substrate having a semipolar plane as its main surface can be obtained. Furthermore, a plurality of semi-polar independent substrates may be obtained by slicing the separation portion 2-2 of the group III nitride semiconductor layer. The slicing position of the separation portion 2-2 for obtaining the group III nitride semiconductor layer can be set, for example, from the interface of the semipolar seed substrate 1 and the group III nitride semiconductor layer 2 along the stacking direction toward the group III nitride semiconductor layer 2 The position after moving 100 μm or more and 500 μm or less is not limited to this.

The plane orientation of the main surface of the semipolar independent substrate may be the same as the plane orientation of the main surface of the semipolar seed substrate 1. In addition, the plane orientation of the main surface of the semipolar independent substrate may be different from the plane orientation of the main surface of the semipolar seed substrate 1. The above can be achieved by adjusting the slope of the slice plane of the slice. For example, when the main surface of the semi-polar seed crystal substrate 1 is a surface with an angle of deviation within 15° from the {hklm} surface (for example: {-1-12-3} surface), the main surface of the semi-polar independent substrate The face can be a {hklm} face.

Furthermore, as shown in FIG. 2(3), after a part of the group III nitride semiconductor layer 2 (the separation part 2-2 of the group III nitride semiconductor layer) is separated from the semipolar seed substrate 1, the group III nitrogen The other part of the compound semiconductor layer 2 (the remaining portion 2-1 of the group III nitride semiconductor layer) remains on the semipolar seed substrate 1.

"Processing step S40" Returning to FIG. 1, the processing step S40 is performed after the cutting step S30 and before performing the group III nitride semiconductor layer forming step S20 using the semipolar seed substrate 1. In the processing step S40, all the group III nitride semiconductor layer 2 is removed from the semipolar seed substrate 1 in which a part of the group III nitride semiconductor layer 2 (the separation part 2-2 of the group III nitride semiconductor layer) remains. For example, the group III nitride semiconductor layer 2 can be removed from the semi-polar seed substrate 1 by polishing.

In the processing step S40, a part of the surface side of the semi-polar seed substrate 1 that is in contact with the group III nitride semiconductor layer 2 can be removed. In this way, the removal of all group III nitride semiconductor layers 2 can be surely achieved.

Furthermore, the processing step S40 may include a process of confirming that all the group III nitride semiconductor layers 2 have been removed from the semipolar seed substrate 1 by surface observation. The surface observation here is, for example, surface observation using SEM (Scanning Electron microscope)/CL (Cathodoluminescence).

After the processing step S40, the semi-polar seed substrate 1 from which all the group III nitride semiconductor layers 2 have been removed is reused to perform the group III nitride semiconductor layer forming step S20 and the cutting step S30. Furthermore, after the semi-polar seed substrate 1 is reused, the group III nitride semiconductor layer forming step S20 and the cutting step S30 can be performed, and then the processing step S40 can be performed to reuse the semi-polar seed substrate 1 a plurality of times. For example, the upper limit of the number of times of repeated use (for example, about 5 times) may be predetermined, and if this number of times is reached, the reuse of the semi-polar seed crystal substrate 1 is ended.

Next, the function and effect of the manufacturing method of the semipolar independent substrate of this embodiment will be described. In the manufacturing method of the semipolar independent substrate of the present embodiment, the group III nitride semiconductor layer 2 is formed on the semipolar seed substrate 1 having the group of the group III nitride semiconductor with the semipolar surface as the main surface, and then the group III The nitride semiconductor layer 2 is separated from the semipolar seed substrate 1 to obtain a semipolar independent substrate, and then this step is performed using the semipolar seed substrate 1 obtained by separating the group III nitride semiconductor layer 2. By reusing the semi-polar seed crystal substrate 1, a cost advantage can be produced.

In the following examples, it is shown that when a group III nitride semiconductor layer is formed by using a c-plane as a growth plane on a seed substrate having a c-plane as a main surface, the obtained group-III nitride semiconductor The surface of the layer is prone to through holes or cracks. As a result, through holes or cracks are easily generated on the surface of the obtained independent substrate.

On the other hand, according to the manufacturing method of this embodiment in which the group III nitride semiconductor layer 2 is formed on the semipolar seed substrate 1 having the semipolar plane as the main surface, the semipolar plane is used as the growth plane, and the above-mentioned c plane Compared with the growth example, the surface of the obtained III-nitride semiconductor layer 2 is less likely to produce through holes or cracks. As a result, the surface of the obtained semipolar independent substrate is also less prone to through holes or cracks. That is, according to the method for manufacturing a semipolar independent substrate of this embodiment, a semipolar independent substrate with a good surface condition can be manufactured.

In addition, according to the manufacturing method of the semipolar independent substrate of the present embodiment, since the semipolar independent substrate whose main surface becomes the semipolar surface can be manufactured, the internal quantum efficiency of the device formed on the independent substrate can be improved.

In addition, according to the manufacturing method of the semi-polar independent substrate of the present embodiment in which the III-nitride semiconductor layer 2 is completely removed from the semi-polar seed substrate 1 before reuse, the III in the III-nitride semiconductor layer forming step S20 In the growth of group nitride semiconductors, the probability of occurrence of local conditions such as strain, abnormal growth, and crystal defects can be reduced. That is, a high-quality semi-polar independent substrate can be manufactured.

<Second Embodiment> The flowchart of FIG. 8 shows an example of the processing flow of the manufacturing method of the semipolar independent substrate of this embodiment. As shown in the figure, in the manufacturing method of the semipolar independent substrate of this embodiment, the preparation step S10, the group III nitride semiconductor layer forming step S20, the cutting step S30, the processing step S40, and the determination step S50 are sequentially performed.

This embodiment is different from the first embodiment in that it has a judgment step S50. The preparation step S10, the group III nitride semiconductor layer forming step S20, the cutting step S30, and the processing step S40 are the same as in the first embodiment.

Furthermore, although not shown, the determination step S50 may be performed after the cutting step S30 and before the processing step S40, rather than after the processing step S40. In addition, the determination step S50 may be performed after the cutting step S30 and before the processing step S40 and after the processing step S40.

By performing the determination step S50 after the cutting step S30 and before the processing step S40, the defect of performing the processing step S40 on the semi-polar seed substrate 1 that cannot be reused can be suppressed. Moreover, since the determination step S50 is performed after the processing step S40, the influence of the processing step S40 can be considered to determine whether the semipolar seed substrate 1 can be reused. Hereinafter, the determination step S50 will be described.

"Judgment Step S50" In the judgment step S50, it is judged whether the semi-polar seed substrate 1 can be reused. When it is determined in step S50 that it is reusable, the semi-polar seed substrate 1 is reused. That is, a group III nitride semiconductor layer 2 is formed on the semipolar seed substrate 1, and a semipolar independent substrate is cut from the group III nitride semiconductor layer 2. On the other hand, when it is determined in the determination step S50 that it cannot be reused, the reuse of the semipolar seed substrate 1 is ended.

Hereinafter, a specific example of the determination method will be described.

In the first example, based on the radius of curvature of the semi-polar seed substrate 1, it is determined whether it can be reused. Specifically, when the radius of curvature of the semipolar seed crystal substrate 1 is greater than or equal to the reference value, it is determined to be reusable, and when the radius of curvature of the semipolar seed crystal substrate 1 does not reach the reference value, it is determined that it is no longer possible use.

If the warpage of the semi-polar seed substrate 1 is too large, the obtained semi-polar independent substrate will also warp to a large extent, and defects such as cracks may occur. By judging whether it can be reused based on the radius of curvature, it is possible to suppress the defect of manufacturing an unsuitable semipolar independent substrate as a product. Furthermore, the reference value of the radius of curvature is, for example, 1 m, and can be appropriately set according to the reference value.

When the judgment step S50 is performed after the cutting step S30 and before the processing step S40, the deviation angle relative to the main surface can be measured by the energy dispersive X-ray diffraction (EDXRD) method, and calculated based on the obtained data Radius of curvature. The X-ray rocking curve method can also be used for measurement, but due to the cutting step S30, cutting damage is generated on the crystal cut surface, and it is difficult to achieve measurement with good accuracy, which is not good.

On the other hand, when the judgment step S50 is performed after the processing step S40, since the cutting damage of the crystal surface is removed by the processing step S40, energy dispersive X-ray diffraction method and X-ray rocking curve method can be used Either method measures the radius of curvature with high accuracy.

In this way, by selecting an appropriate method according to the timing at which the judgment step S50 is performed, the state of the semipolar seed substrate 1 can be properly evaluated.

In the second example, it is determined whether the semi-polar seed crystal substrate 1 has a specific crack or not, and it can be reused. Specifically, when the semi-polar seed crystal substrate 1 does not generate a specific crack, it is determined to be reusable, and when the semi-polar seed crystal substrate 1 generates a specific crack, it is determined to be unusable. The specific crack is, for example, a crack having a predetermined reference length or longer. The reference length may be "more than 50% of the diameter of the semi-polar seed substrate 1", or it may be specified as "more than ○ cm".

If the semipolar seed substrate 1 has a long crack, it will adversely affect the crystallinity of the group III nitride semiconductor layer 2 formed thereon. By judging whether it can be reused based on whether there is a specific crack or not, it is possible to suppress the defect of manufacturing an unsuitable semi-polar independent substrate as a product.

In the third example, based on the thickness of the semi-polar seed substrate 1, it is determined whether it can be reused. Specifically, when the thickness of the semi-polar seed crystal substrate 1 is equal to or greater than the reference value, it is determined to be reusable, and when the thickness of the semi-polar seed crystal substrate 1 does not reach the reference value, it is determined that it is not reusable.

As described in the first embodiment, in the processing step S40, since the removal of all the group III nitride semiconductor layers 2 is surely achieved, it is possible to remove the semi-polar seed substrate 1 that is in contact with the group III nitride semiconductor layer 2 Part of the face side. In this case, by removing a part of the semi-polar seed crystal substrate 1, the semi-polar seed crystal substrate 1 becomes thinner.

If the semi-polar seed crystal substrate 1 becomes too thin, the semi-polar seed crystal substrate 1 or the group III nitride semiconductor layer 2 formed thereon is likely to be warped or cracked. By judging whether it can be reused based on the thickness, it is possible to suppress the defect of manufacturing an unsuitable semipolar independent substrate as a product. Furthermore, the reference value of the thickness is, for example, 250 μm, and can be appropriately set according to the reference value.

In the fourth example, based on the surface roughness of the semi-polar seed substrate 1, it is judged whether it can be reused. Specifically, when the surface roughness of the semi-polar seed crystal substrate 1 does not reach the reference value, it is judged as reusable, and when the surface roughness of the semi-polar seed crystal substrate 1 is above the reference value, it is judged as Cannot be reused.

If the surface roughness of the semi-polar seed crystal substrate 1 is too rough, the crystallinity of the semi-polar seed crystal substrate 1 or the group III nitride semiconductor layer 2 formed thereon is easily damaged. By judging whether it can be reused based on the surface roughness, it is possible to suppress the defect of manufacturing an unsuitable semipolar independent substrate as a product. In addition, the reference value of the surface roughness is, for example, 5×5 μm ^{2 and} the surface roughness RMS (Root Mean Square, root mean square) is 0.5 nm or more and 5 nm or less, and can be appropriately set according to the reference value.

In the fifth example, based on the presence or absence of scratches on the surface of the semi-polar seed substrate 1, it is determined whether it can be reused. Specifically, when scratches are not generated on the surface of the semi-polar seed crystal substrate 1, it is determined to be reusable, and when scratches are generated on the surface of the semi-polar seed crystal substrate 1, it is determined that it cannot be reused.

Through the use of the semi-polar seed crystal substrate 1 or the implementation of the processing step S40, etc., the surface of the semi-polar seed crystal substrate 1 may produce grinding marks or scratches. If there are grinding marks or scratches on the surface of the semi-polar seed substrate 1, it will adversely affect the crystallinity of the group III nitride semiconductor layer 2 formed thereon. By judging whether the scratches on the surface of the semi-polar seed crystal substrate 1 can be reused or not, it is possible to suppress the defect of manufacturing an unsuitable semi-polar independent substrate as a product. The inspection to confirm the presence or absence of scars can be achieved by optical microscope observation or SEM/CL.

According to the manufacturing method of the semipolar independent substrate of the present embodiment described above, the same effect as the first embodiment can be achieved. In addition, according to the method of manufacturing the semi-polar independent substrate of the present embodiment for appropriately determining whether the semi-polar seed substrate 1 can be reused, it is possible to suppress unsuitable manufacturing due to the defective state of the semi-polar seed substrate 1 The semi-polar independent substrate is a defect of the product.

<Example> "Example 1" 9 shows the semi-polar seed substrate 1 of Example 1. FIG. The semi-polar seed substrate 1 of Example 1 contains GaN, and although a part of it has cracks (cracks extending in the longitudinal direction in the figure near the outer periphery of the substrate), there are no through holes. The plane orientation of the main plane is a plane obtained by inclining the {-1-12-3} plane toward the m plane by 9° and 3° toward the c plane, with a diameter of Φ60 mm and a thickness of 800 μm.

On this semi-polar seed substrate 1, GaN is epitaxially grown under the following growth conditions to form a GaN layer (Group III nitride semiconductor layer 2).

Growth method: HVPE method Growth temperature: 1040℃ V/III ratio: 2000/200 Total gas flow: 10314 sccm Impurities: undoped Growth time: 12 hours

10 shows the surface of the GaN layer of Example 1. FIG. There are no through holes or cracks on the surface of the GaN layer. That is, the GaN layer can be formed without generating new through holes or cracks. In addition, cracks existing on the surface of the semipolar seed substrate 1 disappear on the surface of the GaN layer.

After the formation of the GaN layer, as shown in FIG. 11, the slice was sliced at a position moved 300 μm from the interface of the semipolar seed substrate 1 and the GaN layer along the stacking direction toward the GaN layer (upward direction in the figure), The polar seed substrate 1 is separated from a part of the GaN layer. Furthermore, as shown in the figure, the thickness of the central portion of the GaN layer is 2500 μm, and the thickness of the outermost peripheral portion is 1550 μm.

Fig. 12 shows the sliced surface of the separated GaN layer. The circle in the figure represents a circle of Φ50 mm. FIG. 13 shows a sliced surface of the GaN layer remaining on the semipolar seed substrate 1. As shown in FIGS. 12 and 13, no through holes or cracks were confirmed in the GaN layer.

14 shows a semi-polar seed substrate 1 (starting substrate) before performing the formation and separation of the GaN layer, and a semi-polar seed substrate 1 obtained by removing the GaN layer by grinding after performing the formation and separation of the GaN layer ( Reuse the surface of the substrate). Even if the above steps were carried out, it was confirmed that the semipolar seed crystal substrate 1 can be reused without causing scratches or the like on the surface.

"Example 2" 15 shows the semi-polar seed substrate 1 of Example 2. FIG. The semi-polar seed substrate 1 of Example 2 contains GaN, and a part of it has cracks and further has through holes. In the figure, the through holes are indicated by circles. The plane orientation of the main plane is a plane obtained by inclining the {-1-12-3} plane toward the m plane by 9° and 3° toward the c plane, with a diameter of Φ60 mm and a thickness of 800 μm.

On this semi-polar seed substrate 1, GaN is epitaxially grown to form a GaN layer (Group III nitride semiconductor layer 2). The growth conditions are the same as in Example 1 except that the growth time is set twice to 20 hours of growth.

FIG. 16 shows the surface of the GaN layer at a time point when the thickness of the central portion of the laminate including the semipolar seed substrate 1 and the GaN layer is 6 mm. FIG. 17 shows the surface of the GaN layer at the time when the film thickness at the center of the layered product becomes 12.8 mm. In these surfaces, no new through holes or cracks that do not exist in the semi-polar seed substrate 1 are generated.

Furthermore, in the same manner as in Example 1, the semipolar seed crystal was sliced at a position moved 300 μm from the interface of the semipolar seed crystal substrate 1 and the GaN layer along the stacking direction toward the GaN layer (upward direction in the figure). The substrate 1 is separated from a part of the GaN layer.

Fig. 18 shows the sliced surface of the separated GaN layer. There is no through hole or crack in the sliced surface of FIG. 18. That is, the through holes or cracks (see FIG. 15) existing in the semipolar seed crystal substrate 1 disappear.

FIG. 19 shows the slice surface of the GaN layer remaining on the semipolar seed substrate 1. Although there is a through hole (circle in the figure) in the center, there are no other through holes or cracks. That is, the through hole existing in the central portion of the through hole or crack (see FIG. 15) of the semipolar seed crystal substrate 1 remains, and the other through holes or crack disappear.

FIG. 20 shows an optical microscope observation image of the through hole existing in the central portion of the semipolar seed substrate 1. FIG. 21 shows an optical microscope observation image of the through hole existing in the central portion of the slice surface of the GaN layer shown in FIG. 19. In addition, the unit of the number indicating the length in FIGS. 20 and 21 is “μm”. It can be seen from the figure that the width or length of the through hole becomes smaller as the distance away from the semipolar seed substrate 1 (as the group III nitride semiconductor constituting the group III nitride semiconductor layer 2 grows). That is, it was confirmed that by growing the III-nitride semiconductor on the semi-polar seed crystal substrate 1, the through-holes present in the semi-polar seed crystal substrate 1 can be reduced or cracks disappeared. Furthermore, the projection axis of <000-2> in the figure indicates the direction of the axis after projecting <000-2> onto the main surface of the semipolar seed crystal substrate 1. Similarly, the projection axis of <10-10> in the figure represents the direction of the axis after projecting <10-10> onto the main surface of the semipolar seed crystal substrate 1.

"Comparative Example 1" FIG. 22 shows the seed crystal substrate of Comparative Example 1. The seed substrate of Comparative Example 1 contains GaN and has through holes. In the figure, the through holes are indicated by circles. The main surface is the c-plane, the diameter is Φ50 mm, and the thickness is 400 μm.

A GaN layer is formed by epitaxially growing GaN on the seed substrate. The growth conditions are the same as in Example 1 except that the growth time is set to 20 hours and Si doping is performed.

Fig. 23 shows the surface of the GaN layer. It can be seen that the through holes present on the seed substrate also exist in the GaN layer. Furthermore, it can be confirmed that the through hole of the GaN layer is larger than the through hole on the seed substrate.

"Comparative Example 2" FIG. 24 shows the seed substrate of Comparative Example 2. The seed substrate of Comparative Example 2 contains GaN, and there is an opening that does not penetrate to the back surface. The main surface is the c-plane, the diameter is Φ50 mm, and the thickness is 400 μm.

A GaN layer is formed by epitaxially growing GaN on the seed substrate. The growth conditions are the same as in Example 1 except that the growth time is set to 20 hours.

Fig. 25 shows the surface of the GaN layer. It can be confirmed that there is a new through hole (not shown by a circle in the figure) that does not exist on the seed substrate of the GaN layer.

"Comparative Example 3" FIG. 26 shows the seed crystal substrate of Comparative Example 3. FIG. The seed crystal substrate of Comparative Example 3 contains GaN, and there is an opening hole that does not penetrate to the back surface. The main surface is c-plane, the diameter is Φ54 mm, and the thickness is 1.4 mm.

A GaN layer is formed by epitaxially growing GaN on the seed substrate. The growth conditions are the same as in Example 1 except that the growth time is set to 21 hours.

Fig. 27 shows the surface of the GaN layer. It can be confirmed that there is a crack that does not exist on the seed substrate in the GaN layer. In addition, it can be confirmed that there is a through hole that does not exist on the seed crystal substrate, a residual through hole that exists on the seed crystal substrate, and an enlargement of the through hole.

In the following, examples of reference forms are appended. 1. A method for manufacturing a semi-polar independent substrate, which performs: a preparation step, which is to prepare a semi-polar seed substrate with a semi-polar surface as a main surface and containing a group III nitride semiconductor; A step of forming a group III nitride semiconductor layer, which is to epitaxially grow a group III nitride semiconductor on the above semi-polar seed substrate to form a group III nitride semiconductor layer; A cutting step, which is to cut a semipolar independent substrate with a semipolar plane as its main surface from the above-mentioned group III nitride semiconductor layer; and A processing step which is to remove all the group III nitride semiconductor layers from the semi-polar seed substrate remaining a part of the group III nitride semiconductor layer after the cutting step; and then use the group III nitride to remove The semi-polar seed crystal substrate after the semiconductor layer is subjected to the group III nitride semiconductor layer forming step and the cutting step. 2. The manufacturing method of semipolar independent substrate as in 1, which is In the above processing step, a part of the surface side of the semi-polar seed substrate that is in contact with the group III nitride semiconductor layer is removed. 3. The manufacturing method of semi-polar independent substrate like 1 or 2, which is In the above processing steps, the removal of all the above-mentioned Group III nitride semiconductor layers was confirmed by surface observation. 4. The method for manufacturing a semi-polar independent substrate according to any one of 1 to 3, which It further includes a judgment step to judge whether the above semi-polar seed substrate can be reused, When it is judged that it is reusable in the judgment step, the semi-polar seed crystal substrate is reused, When it is determined in the above determination step that it cannot be reused, the reuse of the semi-polar seed substrate is ended. 5. The manufacturing method of semipolar independent substrate as in 4, which is In the above determination step, when the radius of curvature of the semi-polar seed crystal substrate is above a reference value, it is determined to be reusable, and when the radius of curvature of the semi-polar seed crystal substrate does not reach the reference value, it is determined as Cannot be reused. 6. The manufacturing method of semipolar independent substrate as in 4, which is In the above determination step, when the specific crack is not generated in the semi-polar seed crystal substrate, it is determined to be reusable, and when the specific crack is generated in the semi-polar seed crystal substrate, it is determined that it cannot be reused. 7. The manufacturing method of semi-polar independent substrate as in 4, which is In the above determination step, when the thickness of the semi-polar seed substrate is greater than or equal to the reference value, it is determined to be reusable, and when the thickness of the semi-polar seed substrate does not reach the reference value, it is determined that it is no longer possible use. 8. The manufacturing method of semipolar independent substrate as in 4, which is In the above determination step, when the surface roughness of the semi-polar seed crystal substrate does not reach the reference value, it is determined to be reusable, and when the surface roughness of the semi-polar seed crystal substrate is above the reference value, It is judged that it cannot be reused. 9. The manufacturing method of semi-polar independent substrate as in 4, which is In the above determination step, it is determined that the surface of the semi-polar seed crystal substrate is not reusable when scratches are not generated, and when the surface of the semi-polar seed crystal substrate is scratched, it is determined that it is not reusable. 10. The method for manufacturing a semipolar independent substrate according to any one of 1 to 9, wherein The main surface of the above semi-polar seed crystal substrate is a surface having an off angle within 15° from the {hklm} surface, In the above-mentioned cutting step, the above semipolar independent substrate with the {hklm} plane as the main surface is cut. 11. The manufacturing method of the semipolar independent substrate as in 10, wherein The main surface of the above-mentioned semi-polar seed crystal substrate is a surface having a deviation angle within 15° from the {-1-12-3} plane. 12. The method for manufacturing a semipolar independent substrate according to any one of 1 to 11, wherein The above preparation steps include: The fixing step is to fix the base substrate including the group III nitride semiconductor layer with the semipolar plane as the main surface to the base; The first growth step is to fix the group III nitride on the main surface of the group III nitride semiconductor layer by HVPE (Hydride Vapor Phase Epitaxy) method with the base substrate fixed to the pedestal The semiconductor grows to form the first growth layer; The cooling step is to cool the laminate including the susceptor, the base substrate, and the first growth layer; The second growth step is that after the cooling step, the group III nitride semiconductor is grown by the HVPE method on the first growth layer in a state where the base substrate is fixed to the pedestal to form the first 2 Growth layer; and In the cutting step, at least a part of the second growth layer is cut out as the semi-polar seed substrate.

This application claims priority based on Japanese Application No. 2018-158077 filed on August 27, 2018, and incorporates the entire contents of the disclosure.

1: Semi-polar seed substrate 2: Group III nitride semiconductor layer 2-1: Remaining part of III-nitride semiconductor layer 2-2: Separation part of III-nitride semiconductor layer 10: base substrate 11: Sapphire substrate 12: III-nitride semiconductor layer 20: Dock 30: 1st growth layer 31: Crack 40: 2nd growth layer 51: Part 1 52: Part 2 A: area B: area S10: Preparation steps S11: fixation steps S12: 1st growth step S13: cooling step S14: 2nd growth step S15: Seeding substrate cutting step S20: Group III nitride semiconductor layer forming step S30: Cut off the steps S40: Processing steps S50: Judgment step

The above-mentioned object and other objects, features, and advantages are made clearer by the preferred embodiments described below and the drawings attached to it.

FIG. 1 is a flowchart showing an example of the processing flow of the manufacturing method of the semipolar independent substrate of this embodiment. 2(1) to (3) are step diagrams showing an example of the processing flow of the manufacturing method of the semipolar independent substrate of this embodiment. FIG. 3 is a flowchart showing an example of the processing flow of the preparation step of this embodiment. 4(1) to (5) are step diagrams showing an example of the processing flow of the preparation step of this embodiment. 5(1) and (2) are schematic views showing an example of the semi-polar seed substrate of this embodiment. FIG. 6 is a diagram for explaining the configuration of the semi-polar seed crystal substrate of this embodiment. FIG. 7 is a diagram for explaining the configuration of the semi-polar seed substrate of this embodiment. FIG. 8 is a flowchart showing an example of the processing flow of the manufacturing method of the semipolar independent substrate of this embodiment. 9 is a diagram showing the surface of the semipolar independent substrate of Example 1. FIG. 10 is a diagram showing the surface of the GaN layer of Example 1. FIG. Fig. 11 is a diagram for explaining the slicing position of the embodiment. 12 is a diagram showing a sliced surface of the separated GaN layer of Example 1. FIG. 13 is a diagram showing the sliced surface of the GaN layer remaining in the semipolar seed crystal substrate of Example 1. FIG. 14 is a diagram showing the surface of the semipolar seed crystal substrate before use and the semipolar seed crystal substrate before reuse in Example 1. FIG. 15 is a diagram showing the surface of the semipolar independent substrate of Example 2. FIG. 16 is a diagram showing the surface of the GaN layer in the growth stage of Example 2. FIG. 17 is a diagram showing the surface of the GaN layer in the growth stage of Example 2. FIG. 18 is a diagram showing a sliced surface of the separated GaN layer of Example 2. FIG. 19 is a diagram showing a sliced surface of the GaN layer remaining in the semipolar seed crystal substrate of Example 2. FIG. 20 is a diagram showing a through hole existing in the central portion of the semipolar seed substrate of Example 2. FIG. FIG. 21 is a view showing a through hole existing in the center of the slice surface of the GaN layer shown in FIG. 19. 22 is a diagram showing the surface of the seed substrate of Comparative Example 1. FIG. 23 is a diagram showing the surface of the GaN layer of Comparative Example 1. FIG. 24 is a diagram showing the surface of the seed substrate of Comparative Example 2. FIG. 25 is a diagram showing the surface of the GaN layer of Comparative Example 2. FIG. 26 is a diagram showing the surface of the seed substrate of Comparative Example 3. FIG. FIG. 27 is a diagram showing the surface of the GaN layer of Comparative Example 3. FIG.

S10: Preparation steps

S20: Group III nitride semiconductor layer forming step

S30: Cut off the steps

S40: Processing steps

Claims (12)

A method for manufacturing a semi-polar independent substrate, which performs: a preparation step, which is to prepare a semi-polar seed substrate with a semi-polar surface as a main surface and containing a group III nitride semiconductor; A step of forming a group III nitride semiconductor layer, which is to epitaxially grow a group III nitride semiconductor on the above semi-polar seed substrate to form a group III nitride semiconductor layer; A cutting step, which is to cut a semipolar independent substrate with a semipolar plane as its main surface from the above-mentioned group III nitride semiconductor layer; and A processing step which is to remove all the group III nitride semiconductor layers from the semi-polar seed substrate remaining a part of the group III nitride semiconductor layer after the cutting step; and then use the group III nitride to remove The semi-polar seed crystal substrate after the semiconductor layer is subjected to the group III nitride semiconductor layer forming step and the cutting step. For the manufacturing method of semi-polar independent substrate of claim 1, it is In the above processing step, a part of the surface side of the semi-polar seed substrate that is in contact with the group III nitride semiconductor layer is removed. If the manufacturing method of semi-polar independent substrate of claim 1 or 2, it is In the above processing steps, the removal of all the above-mentioned Group III nitride semiconductor layers was confirmed by surface observation. For the manufacturing method of semi-polar independent substrate of claim 1 or 2, It further includes a judgment step to judge whether the above semi-polar seed substrate can be reused, When it is judged that it is reusable in the judgment step, the semi-polar seed crystal substrate is reused, When it is determined in the above determination step that it cannot be reused, the reuse of the semi-polar seed substrate is ended. The manufacturing method of semi-polar independent substrate as claimed in item 4 is In the above determination step, when the radius of curvature of the semi-polar seed crystal substrate is above a reference value, it is determined to be reusable, and when the radius of curvature of the semi-polar seed crystal substrate does not reach the reference value, it is determined as Cannot be reused. The manufacturing method of semi-polar independent substrate as claimed in item 4 is In the above determination step, when the specific crack is not generated in the semi-polar seed crystal substrate, it is determined to be reusable, and when the specific crack is generated in the semi-polar seed crystal substrate, it is determined that it cannot be reused. The manufacturing method of semi-polar independent substrate as claimed in item 4 is In the above determination step, when the thickness of the semi-polar seed substrate is greater than or equal to the reference value, it is determined to be reusable, and when the thickness of the semi-polar seed substrate does not reach the reference value, it is determined that it is no longer possible use. The manufacturing method of semi-polar independent substrate as claimed in item 4 is In the above determination step, when the surface roughness of the semi-polar seed crystal substrate does not reach the reference value, it is determined to be reusable, and when the surface roughness of the semi-polar seed crystal substrate is above the reference value, It is judged that it cannot be reused. The manufacturing method of semi-polar independent substrate as claimed in item 4 is In the above determination step, it is determined that the surface of the semi-polar seed crystal substrate is not reusable when scratches are not generated, and when the surface of the semi-polar seed crystal substrate is scratched, it is determined that it is not reusable. The method for manufacturing a semi-polar independent substrate according to claim 1 or 2, wherein The main surface of the above semi-polar seed crystal substrate is a surface having an off angle within 15° from the {hklm} surface, In the above-mentioned cutting step, the above semipolar independent substrate with the {hklm} plane as the main surface is cut. The method for manufacturing a semi-polar independent substrate according to claim 10, wherein The main surface of the above-mentioned semi-polar seed crystal substrate is a surface having a deviation angle within 15° from the {-1-12-3} plane. The method for manufacturing a semi-polar independent substrate according to claim 1 or 2, wherein The above preparation steps include: The fixing step is to fix the base substrate including the group III nitride semiconductor layer with the semipolar plane as the main surface to the base; The first growth step is to fix the group III nitride on the main surface of the group III nitride semiconductor layer by HVPE (Hydride Vapor Phase Epitaxy) method with the base substrate fixed to the pedestal The semiconductor grows to form the first growth layer; The cooling step is to cool the laminate including the susceptor, the base substrate, and the first growth layer; The second growth step is that after the cooling step, the group III nitride semiconductor is grown by the HVPE method on the first growth layer in a state where the base substrate is fixed to the pedestal to form the first 2 Growth layer; and In the seed crystal substrate cutting step, at least a part of the second growth layer is cut out as the semi-polar seed crystal substrate.

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