JP2009029662A - Method for manufacturing nitride semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a nitride semiconductor substrate having a less fluctuation in the direction of a grating surface in the surface and between substrates from a curved nitride semiconductor crystal. <P>SOLUTION: A layer reformed by processing 13 is introduced into the concave surface of a curved nitride semiconductor crystal 12 grown epitaxially on a different kind of substrate by grinding with diamond abrasives or the like. By introducing the layer reformed by processing 13, the radius of curvature of the nitride semiconductor crystal 12 is enlarged and the grating surface direction [hkil] or [hkl] at each point on the surface is parallelized. From the nitride semiconductor crystal 12 in this state, a plurality of substrates 14 are cut out by slicing from the surface 12a to the back 12b. Because the angle between the surface of the substrate and a specific crystal grating surface becomes almost equal in the surface of the substrate 14 thus obtained, a plurality of substrates 14 having a uniform crystal grating surface can be cut out from the curved nitride semiconductor crystal 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for obtaining a nitride semiconductor substrate with little in-plane variation in the crystal plane direction from a curved nitride semiconductor crystal obtained by epitaxial growth on a different substrate.

  Nitride semiconductor crystals such as gallium nitride (GaN) have been actively studied as materials used in semiconductor devices such as a light source that obtains white color by combining a blue light emitting element and a phosphor. Nitride semiconductor crystals are grown on heterogeneous substrates mainly by epitaxial growth techniques such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor deposition (HVPE). .

  By the way, a nitride semiconductor crystal obtained by epitaxial growth on a heterogeneous substrate is likely to be warped during crystal growth due to a difference in thermal expansion coefficient from a base substrate or lattice mismatch, and is likely to be warped during crystal growth. The nitride semiconductor crystal obtained by crystal growth is greatly warped even in the state of a single film with the base substrate removed.

  As a technique for reducing the curvature of such a curved nitride semiconductor single film, a technique has been reported in which a work-affected layer is formed and flattened by grinding using a diamond grindstone on the surface warped in a concave shape. (Patent Document 1: Japanese Patent Application Laid-Open No. 2005-136167). According to this technique, the geometrical warpage of the nitride semiconductor crystal as a substrate is reduced, for example, from about ± 40 μm to ± 100 μm to about +30 μm to −20 μm.

  Such reduction of the geometrical warpage of the substrate can meet the demands on the device process when forming elements on the substrate. However, from the viewpoint of manufacturing a semiconductor element with a high yield, it is not sufficient to make the substrate geometrically flat. The reason is that in order to achieve the characteristics of the semiconductor device as designed, it is required that the variation in the crystal plane direction is small within the plane of the substrate. However, the substrate is geometrically flat. This is because it does not necessarily mean that there is little variation in the crystal plane direction within the plane of the substrate.

  For example, when a relatively large nitride semiconductor crystal is grown and a plurality of substrates are cut out from the crystal, if the crystal plane direction is different between the central portion and the peripheral portion of the crystal, the substrate is cut out from the crystal. The variation in crystal plane direction among the obtained substrates cannot be ignored but also the crystal plane direction variation between the substrates increases, and the manufacturing yield of semiconductor elements decreases.

In addition, some semiconductor devices are manufactured not on the crystal growth plane but on a special crystal plane that forms a specific angle with the crystal growth plane. It is also difficult to align the orientation with high precision for cutting out a substrate having a crystal plane as a main surface.
JP 2005-136167 A

  The present invention has been made in view of such problems. The object of the present invention is to provide a crystal plane direction in a plane and between substrates from a curved nitride semiconductor crystal obtained by epitaxial growth on a heterogeneous substrate. An object of the present invention is to provide a method for obtaining a plurality of nitride semiconductor substrates with less variation in (lattice plane direction).

  In order to solve such a problem, the method for manufacturing a nitride semiconductor substrate according to the present invention includes a lattice plane direction [hkil] at each point in the plane of a nitride semiconductor crystal obtained by epitaxial growth on a heterogeneous substrate, or A work-affected layer is formed on at least one main surface of the nitride semiconductor crystal so that [hkl] are parallel to each other, and then the nitride semiconductor crystal is cut.

  Preferably, the cutting uses a wire saw and is divided into a plurality of parts at a time in parallel.

  The crystal plane to be cut is, for example, a C plane (polar plane), an A plane or an M plane (nonpolar plane), or a semipolar plane inclined with respect to the C plane.

  In the present invention, preferably, the parallelism in the crystal plane in the lattice plane direction [hkil] or [hkl] is within 1 degree.

  The present invention may further include a step of removing the work-affected layer from the nitride semiconductor substrate.

  The nitride semiconductor crystal is, for example, a gallium nitride based crystal.

  The nitride semiconductor wafer of the present invention is characterized in that, in a nitride semiconductor wafer that is not flat, the lattice plane direction [hkil] or [hkl] at each point in the plane is orthogonal to the use surface.

  The nitride semiconductor wafer of the present invention may have a work-affected layer formed on at least a part of the end face.

  The present invention controls the curvature of a nitride semiconductor crystal by introducing a work-affected layer, and cuts the substrate from the nitride semiconductor crystal in a state in which the lattice plane direction [hkil] or [hkl] is parallelized at each point in the plane. As a result, the angle formed by the substrate surface and the specific crystal lattice plane is substantially the same in the plane of the substrate. For this reason, it is possible to cut out a plurality of substrates having a uniform crystal lattice plane from a curved nitride semiconductor crystal.

  In addition, if the lattice plane direction [hkil] or [hkl] at each point in the plane of the nitride semiconductor crystal is parallel, a plurality of substrates with aligned crystal lattice planes can be simultaneously cut by cutting multiple pieces in parallel with a wire saw. Production efficiency can be improved.

  Furthermore, after a large number of substrates are simultaneously cut out from the nitride semiconductor crystal on which the work-affected layer is formed, the work-affected layer may be removed as necessary. In this case, the cut many substrates are warped again. However, since each cut substrate deforms in substantially the same manner, the variation in crystal plane direction within the cut substrate surface remains unchanged in the curved nitride semiconductor crystal. Compared to a case where a large number of substrates are cut out by slicing a plurality of parallel portions at once, the number can be reduced.

  In general, nitride semiconductor crystals are often epitaxially grown to a certain size, then sliced into thin wafers, and then used to manufacture a large number of semiconductor devices by finely dividing the thin wafer.

  A thin wafer is formed by forming a work-affected layer on the above-mentioned nitride semiconductor crystal and parallelizing the lattice plane direction [hkil] or [hkl] at each point in the plane, and then cutting a plurality of pieces in parallel with a wire saw. When the nitride semiconductor wafer is made by removing the work-affected layer by a surface finishing method usually performed on a semiconductor wafer such as polishing or etching, the nitride semiconductor wafer is warped again as described above. However, since the internal crystal structure is also deformed together with the cut surface of the nitride semiconductor wafer, the angle at which the lattice plane direction [hkil] or [hkl] and the cut surface intersect is the same at each point in the cut surface. It becomes.

  When the cut surface of the nitride semiconductor wafer thus produced is polished and used as a use surface for forming a device, and divided finely on the basis of the cleavage plane, the internal crystal structure of each divided nitride semiconductor crystal Therefore, when a large number of semiconductor elements are manufactured using each of the divided nitride semiconductor crystals, the variation in performance of the semiconductor elements can be reduced.

  However, depending on the purpose of use of the nitride semiconductor wafer, it is not necessary to forcibly remove the work-affected layer.

  In particular, if the work-affected layer comes to the end face portion of the wafer when the nitride semiconductor wafer is made thin, it hardly affects the manufacture of the semiconductor element, so it is not necessary to remove it.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the following description, it is assumed that the crystal type of a nitride semiconductor crystal such as a gallium nitride type is a hexagonal crystal type, and the lattice plane index is represented by (hkil) and the lattice plane direction is represented by [hkil]. Since the crystal can also take a cubic type, in that case, the lattice plane index is represented by (hkl) and the lattice plane direction is represented by [hkl].

  FIGS. 1A to 1E are diagrams for explaining how the nitride semiconductor crystal 12 is curved as the crystal grows when the nitride semiconductor crystal 12 is epitaxially grown on the heterogeneous substrate 11. Here, the heterogeneous substrate 11 is a hexagonal sapphire substrate having a (0001) plane (C plane) as a main surface (FIG. 1A).

  On the sapphire substrate, the same hexagonal nitride semiconductor crystal 12 (here, GaN crystal) as that of the substrate is epitaxially grown in the C-axis direction. The crystal growth proceeds in the same direction (indicated by an arrow in the figure) (FIG. 1B). However, since sapphire and GaN have a lattice mismatch of about 14%, as GaN crystal growth progresses and the film thickness increases, stress is generated inside the GaN crystal, resulting in gradual bending and lattice plane direction [ hkil] (in the direction of the arrow in the figure) begins to vary within the plane (FIGS. 1C to 1D), and when the nitride semiconductor crystal 12 is a thick film, the interface is between the sapphire substrate and the GaN crystal. The sapphire substrate may be naturally peeled off due to the generated stress (FIG. 1E).

  In the nitride semiconductor crystal 12 obtained as a result of such epitaxial growth, the lattice plane direction [hkil] varies from place to place within the plane, and the greater the degree of curvature, the greater the lattice plane direction [hkil]. The in-plane variation (that is, the angle formed by the arrows shown in the figure) increases.

  FIG. 2 shows that a work-affected layer 13 is formed on one main surface of the nitride semiconductor crystal 12 that is curved and epitaxially grown to control the degree of curvature, and thereby the lattice semiconductor direction in the plane of the nitride semiconductor crystal 12 is controlled. It is a figure for demonstrating a mode that the grade of dispersion | variation is reduced, and is on one main surface (surface which was the sapphire substrate side in FIG. 1) of the curved nitride semiconductor crystal 12 (FIG. 2 (A)) after epitaxial growth. A work-affected layer 13 is formed (FIGS. 2B to 2C).

  It is known that when a work-affected layer 13 is introduced on the concave surface side of a curved nitride semiconductor crystal 12 obtained by epitaxial growth, the concave surface expands and is flattened according to the level of work deterioration (see Patent Document 1). In the present invention, the lattice plane directions [hkil] (C-axis direction, ie, the [0001] direction, which is the crystal growth direction indicated by an arrow in the drawing) at each point in the plane of the curved nitride semiconductor crystal 12 are parallel to each other. Thus, the work-affected layer 13 is introduced into the concave surface side of the nitride semiconductor crystal 12 (FIG. 2C). Such a work-affected layer 13 may be introduced not only on the concave side but also on the convex side.

  FIG. 3 is a view for explaining a state in which the substrate is cut out from the nitride semiconductor crystal 12 in which the work-affected layer 13 is introduced and the lattice plane direction [hkil] at each point in the plane is parallelized. ) Is a side view of the nitride semiconductor crystal 12, and FIG. 3B is perpendicular to the front surface 12a to the back surface 12b of the nitride semiconductor crystal 12 after the work-affected layer 13 is introduced (that is, in the lattice plane direction [0001]). The figure which shows a mode that the some board | substrate 14 was obtained by slicing (in parallel), and FIG.3 (C) is a perspective view of the obtained board | substrate 14. FIG.

  The nitride semiconductor crystal 12 has a diameter of, for example, about 60 mm and a thickness of about 5 mm, and the thickness of the substrate cut out from this crystal is, for example, about 0.5 mm. In such a case, the cut substrate 14 has a length L of 60 mm, a width H of 5 mm, and a thickness t of 0.5 mm. In the case of FIG. 3B, since the work-affected layer 13 is at the end face portion of the substrate 14, the work-affected layer 13 is not particularly removed, and the substrate 14 is removed by processes such as corner grinding, surface polishing and etching. Finish. However, if necessary, the work-affected layer 13 may be removed.

  Thereafter, layers having a device function are stacked, and the substrate 14 is divided into 0.2 mm square using, for example, the cleavage plane of the substrate 14 as a reference plane, and used for manufacturing a semiconductor element. As means for dividing, there are methods such as slicing and cleavage.

  In FIG. 3, the substrate surface obtained by slicing is a lattice plane perpendicular to the C plane, but the lattice growth surface of the nitride semiconductor crystal 12 is the surface of the substrate 14 obtained by cutting. Depending on what element is formed in 15, the crystal plane to be cut includes a C plane that is a polar plane, an A plane that is a nonpolar plane (that is, a (11-20) plane), or an M plane (that is, ( 1-100) plane), or a semipolar plane inclined with respect to the C plane.

  As a method of cutting the nitride semiconductor crystal 12, for example, the crystal orientation is examined by using an X-ray diffraction method, and the cutting direction is determined, and a plurality of slices in parallel with a wire saw is preferable because the manufacturing efficiency is improved. Of course, you may slice by another method as needed. Further, in FIG. 3A, the work-affected layer 13 is formed only on one surface, but the work-affected layer 13 may be formed on the opposite surface as necessary.

  FIG. 4 is a diagram for explaining a state in which a wafer-like substrate is cut out from the nitride semiconductor crystal 12 in which the work-affected layer 13 is introduced and the lattice plane direction [hkil] is parallelized at each point in the plane. 4 (A) is a side view of the nitride semiconductor crystal 12, and FIG. 4 (B) is a view from one end 12c to the other end 12d of the side surface of the nitride semiconductor crystal 12 after the work-affected layer 13 is introduced (that is, a lattice plane). FIG. 4C shows a state in which four wafers 14 are obtained by cutting at the same time (perpendicular to the direction [0001]), and FIG. 4C is a perspective view of the obtained wafers 14.

  Since the thickness of the wafer 14 is, for example, about 0.5 mm, the cut wafer 14 has a diameter D of 60 mm, a thickness t of 0.5 mm, and the like. The process-affected layer 13 is removed by a process such as etching, and the wafer 14 is finished. Then, a layer having a device function is laminated, and the wafer 14 is divided into 0.2 mm square using, for example, the cleaved surface of the wafer 14 as a reference plane, and used for manufacturing semiconductor elements. Also in the case of FIG. 4A, the work-affected layer 13 is formed only on one surface, but the work-affected layer 13 may be formed on the opposite surface as necessary.

  That is, processing is performed on the concave surface side of the nitride semiconductor crystal 12 so that the lattice plane directions at each point in the plane of the curved nitride semiconductor crystal 12 (in this figure, the C-axis direction, that is, the [0001] direction) are parallel to each other. The altered layer 13 is introduced, and a substrate is obtained by cutting out a plurality of wafers simultaneously in this state.

  Here, a plurality of wafers are simultaneously cut out from the nitride semiconductor crystal 12 because the effect of the crystals being curved changes depending on the thickness of the nitride semiconductor crystal 12, so that the wafers are cut out one by one. In this case, the balance between the effect of expanding the concave surface due to the work-affected layer 13 and the effect of the crystal attempting to bend is lost, and the parallelism in the lattice plane direction at each point in the plane of the nitride semiconductor crystal 12 during the process of cutting the wafer. This is because of the decrease.

  In the present invention, the parallelism in the crystal plane in the lattice plane direction [hkil] (or [hkl]) is preferably within 1 degree. With this degree of parallelism, when a plurality of layers having a device function are laminated on the cut wafer by, for example, the HVPE method or the MOVPE method, the interface between the layers can be easily formed flat. However, when the parallelism exceeds 1 degree, it becomes difficult to form the interface of each layer flatly, and unevenness is easily formed on the interface. For example, when a light emitting element is used, the emission intensity is lowered. Further, if the parallelism of the cut wafer exceeds 1 degree, the crystal structure itself of the layer formed on the wafer is affected, and the amount of dopant substance mixed in the layer at the time of layer formation is biased. Similarly, luminance unevenness occurs when a light emitting element is used.

  Further, after obtaining the nitride semiconductor substrate, the work-affected layer portion remaining on the substrate may be removed. If the work-affected layer portion is removed after obtaining the substrate, the substrate (and thus the element formation surface) may be geometrically curved, but even if such a curvature occurs, the lattice This is because the surface is in the same curved state as the substrate surface, and the relationship between the substrate surface and the lattice plane when viewed locally is maintained in a substantially constant relationship within the substrate surface.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  Using a sapphire substrate having a diameter of 60 mm with the C-plane as the main surface, a GaN crystal was epitaxially grown in the C-axis direction to obtain a crystal having a thickness of about 5 mm. This substrate had a C-shaped side curved in a concave shape, and its curvature radius was about 3 m as evaluated by X-ray diffraction. A work-affected layer was introduced by grinding the entire surface of the GaN crystal on the concave curved side with a diamond abrasive having a grain size of 30 to 40 μm to a depth of 0.05 mm. An infinite number of fine cracks having a depth of several μm to several tens of μm were formed on the ground crystal surface, and the curvature of the GaN crystal was relaxed to a radius of curvature of about 5 m. That is, the parallelism in the crystal plane in the lattice plane direction [0001] was about 0.7 degrees.

  A substrate having an M-plane surface was cut out from the crystal in this state. Specifically, the orientation of the crystal was adjusted by X-ray diffraction, and five substrates were sliced at once with a wire saw so as to cross the front and back surfaces of the crystal, and the surface was polished.

  FIG. 5 is a graph for explaining the result of examining the degree of variation in angle between the substrate surface and a specific crystal lattice plane (M plane in the present embodiment) in the plane of the obtained substrate by the X-ray diffraction method. 5A, as shown in FIG. 5A, for a total of five points, the center point (a) of the in-plane (polished surface) of the substrate and the points (b, c, d, e) around the substrate, M The angle (θ in FIG. 5B) formed by the surface (indicated as (hkil) in the figure) and the polished surface (S) was examined by a micro X-ray diffraction technique.

  In the case of the substrate obtained in this example, the maximum angle formed by the M surface and the polished surface was 0.5 °. On the other hand, in the case of the substrate cut out without introducing the work-affected layer, the maximum value of the angle formed by the M surface and the polished surface was 1.0 °.

  The growth conditions were changed from those in Example 1 to obtain a GaN crystal epitaxially grown in the C-axis direction having a radius of curvature of about 15 m, a diameter of 60 mm, and a thickness of about 5 mm. The substrate used was a sapphire substrate having a diameter of 60 mm with the C surface as the main surface, as in Example 1. A work-affected layer was introduced by grinding the entire surface of the concavely curved surface (C surface) of this GaN crystal with a diamond abrasive grain having a grain size of 30 to 40 μm to a depth of 0.05 mm.

  An infinite number of fine cracks having a depth of several μm to several tens of μm are formed on the ground crystal surface, and the crystal is deformed in a direction in which the surface on which the crack is formed (C surface) is widened, and is concave. The C surface side became convex. When this curvature was measured by an X-ray diffraction method, the radius of curvature, which was about 15 m, became about 25 m in the opposite direction.

  Next, a work-affected layer was introduced by grinding 0.02 mm in depth with diamond abrasive grains having a particle size of 3 to 5 μm on the entire surface opposite to the crystal plane (the −C plane). The crystal was deformed again by this treatment, and the curvature of the C plane was measured again by the X-ray diffraction method. The radius of curvature was about 45 m. That is, the parallelism in the crystal plane in the lattice plane direction [0001] was about 0.1 degree.

  A substrate having an A-plane surface was cut out from the crystal in this state. Specifically, the orientation of the crystal was adjusted by X-ray diffraction, and five substrates were sliced at once with a wire saw so as to cross the front and back surfaces of the crystal, and the surface was polished.

  As a result of examining the degree of variation in the angle between the substrate surface and the A surface by the X-ray diffraction method by the above-described method, in the case of the substrate obtained in this example, the angle formed by the M surface and the polished surface is The maximum value was 0.1 °. On the other hand, in the case of the substrate cut out without introducing the work-affected layer, the maximum value of the angle formed by the M surface and the polished surface was 0.3 °.

  The growth conditions were changed from those in Examples 1 and 2, and a GaN crystal having a radius of curvature of about 10 m and epitaxially grown in the C-axis direction having a diameter of 60 mm and a thickness of about 5 mm was obtained. The substrate used was a sapphire substrate having a diameter of 60 mm with the C surface as the main surface, as in Examples 1 and 2. A work-affected layer was introduced by grinding the entire surface of the concavely curved surface (C surface) of this GaN crystal with a diamond abrasive grain having a grain size of 30 to 40 μm to a depth of 0.05 mm.

  An infinite number of fine cracks having a depth of several μm to several tens of μm are formed on the ground crystal surface, and the crystal is deformed in a direction in which the surface on which the crack is formed (C surface) is widened, and the curvature becomes X When measured by the line diffraction method, the radius of curvature, which was about 10 m, was about 45 m.

  A plurality of wafers were obtained by slicing 5 pieces at a time with a wire saw along the grinding surface (C surface) from one end to the other end of the crystal. Among these wafers, when polishing was performed to remove the work-affected layer from the wafer in which the work-affected layer was introduced, the curved state of the surface on the C plane returned to the state immediately after crystal growth. At this time, along with the curvature of the surface on the C-plane side, the curved state of the crystal lattice plane inside the GaN crystal also returns to the state immediately after growth, and the angle formed by the surface on the C-plane side and the specific crystal lattice plane is C It became almost the same on the entire surface.

  In addition, the curved state on the C-plane side of another wafer obtained by slicing the work-affected layer by slicing has also returned to the state immediately after growth, and the angle formed by the surface on the C-plane side and the specific crystal lattice plane Was substantially the same on the entire C side.

  A semiconductor element was formed on the wafer thus obtained, and divided into 0.2 mm squares by cleaving or slicing based on the crystal axis to obtain chips. The obtained chips had substantially the same angle relationship between the surface and the specific crystal lattice plane, and there was almost no variation in the performance of the manufactured semiconductor elements.

  In each of the above examples, a GaN crystal epitaxially grown in the C-axis direction was used. However, the present invention can be applied to a GaN crystal grown in the M-axis direction, the A-axis direction, or the -C-axis direction. The invention is applicable. In addition to the GaN crystal, a similar effect can be obtained with a nitride semiconductor crystal such as an AlN crystal or InN crystal. Furthermore, the present invention is applicable to the production of a nitride semiconductor substrate having an off angle.

  According to the present invention, there is provided a method for obtaining a plurality of nitride semiconductor substrates having little variation in crystal plane direction (lattice plane direction) within a plane and between substrates, from curved nitride semiconductor crystals obtained by epitaxial growth on different substrates. Provided.

It is a figure for demonstrating a mode that a nitride semiconductor crystal curves as crystal growth, when a nitride semiconductor crystal is epitaxially grown on a dissimilar substrate. It is a figure for demonstrating a mode that the grade of the dispersion | variation in the lattice plane direction in the surface of a nitride semiconductor crystal is reduced by the work-affected layer introduced into one main surface of the nitride semiconductor crystal curved and epitaxially grown. It is a figure for demonstrating a mode that a board | substrate is cut out from the nitride semiconductor crystal which introduce | transduced the work-affected layer and parallelized the lattice plane direction [hkil] in each point in the surface. It is a figure for demonstrating a mode that a wafer-like board | substrate is cut out from the nitride semiconductor crystal which introduce | transduced the work-affected layer and parallelized the lattice plane direction [hkil] at each point in the surface. It is a figure for demonstrating the result of having investigated the extent of the dispersion | variation in the angle which the board | substrate surface and specific crystal lattice plane make in the surface of a board | substrate by the X ray diffraction method.

Explanation of symbols

11 Dissimilar substrate 12 Nitride semiconductor crystal 13 Worked layer 14 Nitride semiconductor substrate 15 Substrate surface

Claims (8)

Processing is performed on at least one main surface of the nitride semiconductor crystal so that the lattice plane directions [hkil] or [hkl] at each point in the plane of the nitride semiconductor crystal obtained by epitaxial growth on a different substrate are parallel to each other. A method for producing a nitride semiconductor substrate, comprising forming a deteriorated layer and then cutting the nitride semiconductor crystal. The method of manufacturing a nitride semiconductor substrate according to claim 1, wherein the cutting uses a wire saw and divides a plurality of parts at a time in parallel. The nitride semiconductor according to claim 1, wherein the crystal plane to be cut is a C plane (polar plane), an A plane or an M plane (nonpolar plane), or a semipolar plane inclined with respect to the C plane. A method for manufacturing a substrate. 4. The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the parallelism in the crystal plane of the lattice plane direction [hkil] or [hkl] is within 1 degree. The method for manufacturing a nitride semiconductor substrate according to claim 1, further comprising a step of removing the work-affected layer from the nitride semiconductor substrate. The method for manufacturing a nitride semiconductor substrate according to claim 1, wherein the nitride semiconductor crystal is a gallium nitride-based crystal. A nitride semiconductor wafer having a lattice plane direction [hkil] or [hkl] at each point in the plane orthogonal to a use plane in a nitride semiconductor wafer that is not flat. The nitride semiconductor wafer according to claim 7, wherein a work-affected layer is formed on at least a part of the end face.

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