JP2012054563A - Nitride crystal and method for manufacturing nitride crystal substrate with epitaxial layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a nitride crystal having a crystal surface layer directly and surely evaluated so as to suitably be used as a substrate for a semiconductor device without damaging the crystal, and a nitride crystal substrate with an epitaxial layer.SOLUTION: The method for manufacturing the nitride crystal improves the crystallinity of a surface layer 1a in the nitride crystal deteriorated by machining by performing chemical-mechanical polishing after machining the nitride crystal 1. A slurry with pH of 6 or less and 8 or more is determined to be used in the chemical-mechanical polishing. The crystallinity of the surface layer 1a of the nitride crystal 1 improves so that the nitride crystal has uniform distortion of 2.1×10or less on the surface layer of the crystal obtained by X-ray diffraction measurement for varying the X-ray penetration depth from the surface of the crystal, while satisfying X-ray diffraction conditions of an arbitrary specific crystal lattice plane of the nitride crystal.

Description

  The present invention relates to a method for manufacturing a nitride crystal and a nitride crystal substrate with an epi layer, and in particular, a nitride crystal and a nitride crystal substrate with an epi layer that can be preferably used as a substrate for epitaxial crystal growth when manufacturing a semiconductor device. It relates to a manufacturing method.

  As is well known, various semiconductor devices using nitride semiconductor crystals have been manufactured in recent years, and nitride semiconductor light emitting devices have been manufactured as typical examples of such semiconductor devices.

  In the manufacture of a nitride semiconductor device, generally, a plurality of nitride semiconductor layers are epitaxially grown on a substrate. The crystal quality of the epitaxially grown nitride semiconductor layer is affected by the state of the surface layer of the substrate used for the epitaxial growth, and affects the performance of the semiconductor device including the nitride semiconductor layer. Therefore, when a nitride semiconductor crystal is used as such a substrate, it is desirable that at least the main surface of the substrate serving as the base for epitaxial growth does not contain distortion and is smooth.

  That is, the main surface of the nitride semiconductor substrate used for epitaxial growth is generally subjected to smoothing processing and distortion removal processing. In this case, the gallium nitride semiconductor is relatively hard among the compound semiconductors, and the surface smoothing process is not easy, and the distortion removing process after the smoothing process is not easy.

Japanese Patent Application Laid-Open No. 2004-311575 of Patent Document 1 discloses a polishing method using soft abrasive grains and hard abrasive grains as a polishing composition for polishing a surface of a gallium nitride substrate, and a composition thereof. In addition, in US Pat. No. 6,596,079 of Patent Document 2, when a substrate is produced from an (AlGaIn) N bulk crystal grown by vapor phase epitaxy on an (AlGaIn) N seed crystal, a mechanically polished substrate is used. A method of forming a substrate surface having an RMS (root mean square) surface roughness of 1 nm or less by removing surface damage by subjecting the surface to CMP (Chemical Mechanical Polishing) or etching is disclosed. . US Pat. No. 6,488,767 of Patent Document 3 discloses an Al _x Ga _y In _z N (0 <y ≦ 1, x + y + z = 1) substrate having an RMS surface roughness of 0.15 nm by CMP treatment. The CMP treating agent includes Al ₂ O ₃ abrasive grains, SiO ₂ abrasive grains, a pH adjusting agent, and an oxidizing agent. In Japanese Patent Application Laid-Open No. 2001-322899 of Patent Document 4, after the GaN substrate is polished, the work-affected layer is removed by dry etching to finish the substrate surface.

  Conventionally, as described above, a GaN substrate having a substrate surface finished by removing the work-affected layer during mechanical polishing is obtained by mechanically polishing the GaN crystal and then performing CMP treatment or dry etching. However, CMP processing is slow in processing rate, and there are problems in cost and productivity. In dry etching, there is a problem of surface roughness.

  That is, the finishing method by CMP of the Si substrate and the polishing agent in that method are not suitable for a hard nitride semiconductor substrate, and slows the removal rate of the surface layer. In particular, GaN is chemically stable and is not easily etched by wet etching. Further, although the surface of the nitride semiconductor can be removed by dry etching, there is no effect of flattening the surface in the horizontal direction, so that surface smoothing cannot be obtained.

  Further, as described above, in order to epitaxially grow a good crystalline compound semiconductor layer on a substrate surface, it is necessary to use a substrate surface having a surface layer having a good crystal quality with less processing damage and less distortion. is there. However, the crystal quality of the surface layer required on the substrate surface is not clear.

  Conventionally, the distortion of the surface layer of the crystal has been evaluated by Jpn. J. Appl. Phys., Vol. 39, November 2000, p.L1141-L1142 of Non-Patent Document 1 and the academic paper of Japan Ceramic Society of Non-Patent Document 2. Journal, 99, [7], (1991), p.613-619, etc., was performed by cleaving the crystal and observing the cleavage plane with a TEM (transmission electron microscope). That is, the conventional strain evaluation of the surface layer of the crystal has been performed by a destructive test that destroys the crystal, so even if the evaluation result is bad, it cannot be corrected after the evaluation, and the product itself cannot be evaluated. There was a problem. Also. At present, there is no index for nondestructively evaluating the crystallinity of the surface layer on the finished substrate surface, and it is difficult to quantitatively define the crystal quality of the surface layer.

Japanese Patent Laid-Open No. 2004-311575 US Pat. No. 6,596,079 US Pat. No. 6,488,767 JP 2001-322899 A

S. S. Park, two others, “Free-Standing GaN Substrate by Hydride Vapor Phase Epitaxy”, Jpn. J. Appl. Phys., The Japan Society of Applied Physics, Vol. 39, November 2000, p.L1141-L1142. Yutaka Takahashi and three others, "Electron microscopic observation of surface damage in wet polishing of aluminum nitride polycrystalline substrates", Journal of the Ceramic Society of Japan, The Ceramic Society of Japan, 99, [7], (1991), p.613- 619.

  INDUSTRIAL APPLICABILITY The present invention relates to nitride crystals having a crystal surface layer directly and reliably evaluated without damaging the crystals and nitriding with an epi layer so that they can be preferably used as a substrate for epitaxial crystal growth in manufacturing semiconductor devices. It is an object of the present invention to provide a method for manufacturing a physical crystal substrate.

According to one aspect of the present invention, a method for producing a nitride crystal includes machining a nitride crystal grown by a vapor phase growth method or a liquid phase growth method, followed by chemical mechanical polishing, and machining. A nitride crystal manufacturing method for improving crystallinity of a deteriorated nitride crystal surface layer by chemical mechanical polishing, wherein a slurry having a pH of 6 or less or 8 or more in chemical mechanical polishing is used. The improvement in the crystallinity of the surface layer of the specific crystal lattice plane obtained by X-ray diffraction measurement that changes the X-ray penetration depth from the crystal surface while satisfying the X-ray diffraction condition of any specific crystal lattice plane of the crystal Is expressed by a value of | d ₁ −d ₂ | / d ₂ obtained from a surface distance d ₁ at an X-ray penetration depth of 0.3 μm and a surface distance d ₂ at an X-ray penetration depth of 5 μm. 1. Uniform distortion of the surface layer of the crystal It can be 1 × 10 ⁻³ or less.

According to another aspect of the present invention, a method for producing a nitride crystal includes mechanically polishing a nitride crystal grown by a vapor phase growth method or a liquid phase growth method, and then mechanically polishing the nitride crystal. A method for producing a nitride crystal that improves the crystallinity of a surface layer of a nitride crystal that has deteriorated due to processing by chemical mechanical polishing, wherein nitriding is performed using a slurry having a pH of 6 or less or 8 or more in chemical mechanical polishing. The crystallinity of the surface layer of the product crystal is improved by the specific crystal obtained from the X-ray diffraction measurement that changes the X-ray penetration depth from the surface of the crystal while satisfying the X-ray diffraction condition of any specific crystal lattice plane of the crystal. in the diffraction intensity profile of the lattice plane obtained from the half value width v ₂ Metropolitan diffraction intensity peak at the half-width v ₁ and 5 [mu] m X-ray penetration depth of the diffraction intensity peak at the X-ray penetration depth of 0.3 [mu] m | v ₁ −v ₂ The nonuniform strain of the surface layer of the crystal represented by the value of | can be set to 150 arcsec or less.

According to another aspect of the present invention, a method for producing a nitride crystal includes mechanically polishing a nitride crystal grown by a vapor phase growth method or a liquid phase growth method, and then mechanically polishing the nitride crystal. A method for producing a nitride crystal that improves the crystallinity of a surface layer of a nitride crystal that has deteriorated due to processing by chemical mechanical polishing, wherein nitriding is performed using a slurry having a pH of 6 or less or 8 or more in chemical mechanical polishing. The crystallinity improvement of the surface layer of the product crystal is 0.3 μm in the rocking curve measured by changing the X-ray penetration depth from the surface of the crystal with respect to the X-ray diffraction of any specific crystal lattice plane of the crystal. A specific crystal represented by the value of | w ₁ −w ₂ | obtained from the half width w ₁ of the diffraction intensity peak at the X-ray penetration depth and the half width w ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm. The surface orientation deviation is 4 It can be a 0arcsec below.

  In the method for producing a nitride crystal of the above aspect, the slurry includes hypochlorous acid, chlorinated isocyanuric acid, chlorinated isocyanurate, permanganate, dichromate, bromate, thiosulfate, nitric acid, One or more oxidizing agents selected from the group consisting of hydrogen peroxide and ozone can be included.

According to still another aspect of the present invention, a method for manufacturing an epilayer-attached nitride crystal substrate satisfies the X-ray diffraction conditions of any specific crystal lattice plane of a nitride crystal as the nitride crystal substrate. However, the interplanar spacing d ₁ at an X-ray penetration depth of 0.3 μm and an X-ray penetration of 5 μm at a specific crystal lattice plane spacing obtained by X-ray diffraction measurement changing the X-ray penetration depth from the crystal surface. A crystal having a uniform distortion of the surface layer of the crystal represented by | d ₁ −d ₂ | / d ₂ obtained from the interplanar spacing d ₂ in the depth of 2.1 × 10 ⁻³ or less, Including a step of epitaxially growing one or more semiconductor layers on at least one main surface of the nitride crystal substrate.

According to still another aspect of the present invention, a method for manufacturing an epilayer-attached nitride crystal substrate satisfies the X-ray diffraction conditions of any specific crystal lattice plane of a nitride crystal as the nitride crystal substrate. In the diffraction intensity profile of the specific crystal lattice plane obtained from the X-ray diffraction measurement that changes the X-ray penetration depth from the crystal surface, the half-value width v ₁ of the diffraction intensity peak at the X-ray penetration depth of 0.3 μm A crystal having a nonuniform strain of the surface layer of the crystal represented by the value of | v ₁ −v ₂ | obtained from the half-value width v ₂ of the diffraction intensity peak at an X-ray penetration depth of 5 μm is selected. And a step of epitaxially growing one or more semiconductor layers on at least one main surface side of the nitride crystal substrate.

According to still another aspect of the present invention, a method of manufacturing an epilayer-attached nitride crystal substrate is a nitride crystal substrate, which is a nitride crystal, and is related to X-ray diffraction of any specific crystal lattice plane of the crystal. In the rocking curve measured by changing the X-ray penetration depth from the surface, the half-value width w ₁ of the diffraction intensity peak at the X-ray penetration depth of 0.3 μm and the diffraction intensity peak at the X-ray penetration depth of 5 μm A crystal having a plane orientation deviation of a specific crystal lattice plane represented by a value of | w ₁ −w ₂ | obtained from the half-value width w ₂ of 400 arcsec or less is selected, and at least one main surface of the nitride crystal substrate And a step of epitaxially growing one or more semiconductor layers on the side.

In the method for manufacturing a nitride crystal substrate with an epi layer according to the above aspect, the relationship between the lattice constant k ₀ of the nitride crystal substrate and the lattice constant k of the semiconductor layer is (| k−k ₀ | / k) ≦ 0.15. can do.

  According to the present invention, a nitride crystal and an epi layer having a crystal surface layer directly and reliably evaluated without destroying the crystal so that they can be preferably used as a substrate for epitaxial crystal growth in manufacturing a semiconductor device. A method for producing an attached nitride crystal substrate can be provided. That is, a semiconductor device with good characteristics can be obtained by using the nitride crystal according to the present invention as a substrate.

It is a cross-sectional schematic diagram which shows the state of the crystal | crystallization from the crystal | crystallization surface to a depth direction. It is a schematic diagram which shows the measurement axis and the measurement angle in the X-ray diffraction method concerning this invention. It is a schematic diagram which shows the relationship between the uniform distortion of the crystal lattice of the nitride crystal in a X-ray diffraction method, and the space | interval of the specific crystal lattice plane in a diffraction profile. Here, (a) shows the uniform distortion of the crystal lattice, and (b) shows the interplanar spacing of the specific crystal lattice plane in the diffraction profile. It is a schematic diagram which shows the relationship between the non-uniform distortion of the crystal lattice of the nitride crystal in a X-ray diffraction method, and the half width of the diffraction peak in a diffraction profile. Here, (a) shows non-uniform distortion of the crystal lattice, and (b) shows the half width of the diffraction peak in the diffraction profile. It is a schematic diagram which shows the relationship between the plane orientation shift | offset | difference of the specific crystal lattice plane of the nitride crystal in a X-ray diffraction method, and the half value width in a rocking curve. Here, (a) shows the plane orientation deviation of the specific crystal lattice plane, and (b) shows the half width in the rocking curve. It is a cross-sectional schematic diagram which shows an example of the semiconductor device concerning this invention.

  In the present invention, by using the X-ray diffraction method, the crystallinity in the surface layer of the nitride crystal can be directly evaluated without destroying the crystal. Here, the evaluation of crystallinity means evaluating the degree of crystal distortion, and specifically, evaluating the degree of crystal lattice distortion and crystal plane misalignment. That means. The crystal lattice distortion includes a uniform strain in which the crystal lattice is uniformly distorted and a non-uniform strain in which the crystal lattice is distorted non-uniformly. The crystal orientation deviation of the crystal lattice plane refers to the magnitude of variation in which the plane orientation of the lattice plane of each crystal lattice is deviated from the average orientation of the plane orientation of the crystal plane of the entire crystal lattice.

  As shown in FIG. 1, the nitride crystal 1 is processed by cutting, grinding, polishing, or the like to form a uniform strain, non-uniform strain in the crystal lattice, and / or strain from the crystal surface 1s to the crystal surface layer 1a in a certain depth direction. Surface orientation deviation occurs. In addition, the crystal surface adjacent layer 1b adjacent to the crystal surface layer 1a may have at least one of a uniform distortion of the crystal lattice, a non-uniform distortion of the crystal lattice, and a plane orientation shift of the crystal lattice (FIG. (Indicates a case where a plane orientation deviation has occurred). Further, the inner crystal layer 1c inside the crystal surface adjacent layer 1b is considered to have the original crystal structure of the crystal. Note that the state and thickness of the crystal surface layer 1a and the crystal surface adjacent layer 1b differ depending on the grinding method or polishing method in surface processing.

  Here, the crystallinity of the crystal surface layer can be directly and reliably evaluated by evaluating the uniform strain, nonuniform strain, and / or plane orientation deviation of the crystal lattice in the depth direction from the crystal surface. .

  In the present invention, the X-ray diffraction measurement for evaluating the crystallinity of the surface layer of the nitride crystal is performed by the X-ray penetration from the surface of the crystal while satisfying the X-ray diffraction condition of any specific crystal lattice plane of the nitride crystal. It changes the depth.

  Here, the diffraction condition of an arbitrary specific crystal lattice plane refers to a condition in which X-rays are diffracted by the arbitrarily specified crystal lattice plane, the Bragg angle is θ, the X-ray wavelength is λ, and the crystal lattice plane is X is diffracted at a crystal lattice plane that satisfies Bragg's conditional expression (2 d sin θ = nλ, where n is an integer).

  The X-ray penetration depth refers to the distance in the vertical depth direction from the crystal surface 1s when the intensity of incident X-rays is 1 / e (e is the base of natural logarithm). The X-ray penetration depth T is determined by referring to FIG. 2. The X-ray absorption coefficient μ of the nitride crystal 1, the tilt angle χ of the crystal surface 1 s, the X-ray incident angle ω with respect to the crystal surface 1 s, and the Bragg angle θ Is expressed as in equation (1). The χ axis 21 is in the plane formed by the incident X-ray 11 and the outgoing X-ray 12, and the ω axis (2θ axis) 22 is perpendicular to the plane formed by the incident X-ray 11 and the outgoing X-ray 12. The φ axis 23 is perpendicular to the crystal surface 1s. φ indicates the rotation angle within the crystal surface 1s.

  Therefore, the X-ray penetration depth T can be continuously changed by adjusting at least one of χ, ω, and φ so as to satisfy the diffraction condition for the specific crystal lattice plane.

  In order to continuously change the X-ray penetration depth T so as to satisfy the diffraction condition on the specific crystal lattice plane 1d, it is necessary that the specific crystal lattice plane 1d and the crystal surface 1s are not parallel to each other. . When the specific crystal lattice plane and the crystal surface are parallel, the angle θ formed by the specific crystal lattice plane 1d and the incident X-ray 11 and the angle ω formed by the crystal surface 1s and the incident X-ray 11 are the same. Thus, the X-ray penetration depth cannot be changed at the specific crystal lattice plane 1d.

  Here, the X-ray penetration depth is changed to irradiate any specific crystal lattice plane of the crystal with X-rays, and the uniform distortion of the crystal lattice is determined from the change in interplanar spacing in the diffraction profile for the specific crystal lattice plane. Based on the following embodiments, the evaluation of non-uniform distortion of the crystal lattice from the change in half-value width of the diffraction peak in FIG. To do.

(Embodiment 1)
The nitride crystal of the present embodiment has a specific crystal lattice plane obtained by X-ray diffraction measurement that changes the X-ray penetration depth from the crystal surface while satisfying the X-ray diffraction condition of any specific crystal lattice plane of the crystal. It is expressed by a value of | d ₁ −d ₂ | / d ₂ obtained from a surface distance d ₁ at an X-ray penetration depth of 0.3 μm and a surface distance d ₂ at an X-ray penetration depth of 5 μm. The uniform strain of the surface layer of the crystal is 2.1 × 10 ⁻³ or less.

Referring to FIG. 1, an X-ray penetration depth of 0.3 μm corresponds to a distance from the surface of the nitride crystal to the crystal surface layer 1a, and an X-ray penetration depth of 5 μm corresponds to the nitride crystal surface from the surface of the nitride crystal 1c. It corresponds to the distance to the inside. At this time, referring to FIG. 3A, the interplanar spacing d ₂ at the X-ray penetration depth of 5 μm is considered to be the spacing of the specific crystal lattice plane inherent in the nitride crystal. The interplanar spacing d ₁ at 3 μm reflects the uniform distortion of the crystal lattice of the crystal surface layer due to the influence of surface processing of the crystal (for example, tensile stress 30 in the crystal lattice plane direction), and the X-ray penetration depth is 5 μm. A value different from the surface distance d _{2 at} .

In the above case, referring to FIG. 3B, in the diffraction profile for an arbitrary specific crystal lattice plane of the crystal, the plane distance d ₁ at the X-ray penetration depth of 0.3 μm and the plane at the X-ray penetration depth of 5 μm An interval d ₂ appears. Accordingly, there is a ratio of the difference between d ₁ and d ₂ for d ₂ | d ₁ -d ₂ | by / d ₂ values, it is possible to represent the uniform distortion of the crystal surface layer.

In the nitride crystal of the present embodiment, the uniform distortion of the surface layer represented by the value of | d ₁ −d ₂ | / d ₂ is 2.1 × 10 ⁻³ or less. By setting the uniform strain of the surface layer of the nitride crystal to | d ₁ −d ₂ | / d ₂ ≦ 2.1 × 10 ⁻³ , a semiconductor layer with good crystallinity can be epitaxially grown on the nitride crystal. And a semiconductor device with good characteristics can be manufactured.

(Embodiment 2)
The nitride crystal of the present embodiment has a specific crystal lattice plane obtained by X-ray diffraction measurement that changes the X-ray penetration depth from the crystal surface while satisfying the X-ray diffraction condition of any specific crystal lattice plane of the crystal. in the diffraction intensity profile obtained from half-value width v ₂ Metropolitan diffraction intensity peak at the half-width v ₁ and 5 [mu] m X-ray penetration depth of the diffraction intensity peak at the X-ray penetration depth of 0.3 [mu] m | v ₁ -v ₂ The non-uniform distortion of the surface layer of the crystal represented by the value of | is 150 arcsec or less.

Referring to FIG. 1, an X-ray penetration depth of 0.3 μm corresponds to a distance from the surface of the nitride crystal to the crystal surface layer 1a, and an X-ray penetration depth of 5 μm corresponds to the nitride crystal surface from the surface of the nitride crystal 1c. It corresponds to the distance to the inside. At this time, referring to FIG. 4A, the half-value width v ₂ of the diffraction peak at an X-ray penetration depth of 5 μm is considered to be the original half-value width of the nitride crystal. The half-value width v ₁ of the diffraction peak at 3 μm is the non-uniform distortion of the crystal lattice of the crystal surface layer due to the influence of the surface processing of the crystal (for example, the interplanar spacing of each crystal lattice plane is d ₃ , d _{4 to} d ₅ , Reflecting d ₆ ), it takes a value different from the half-value width v ₂ of the diffraction peak at an X-ray penetration depth of 5 μm.

In the above case, referring to FIG. 4B, in the diffraction profile for an arbitrary specific crystal lattice plane of the crystal, the half-value width v ₁ of the diffraction peak and the X-ray penetration depth at an X-ray penetration depth of 0.3 μm A half-value width v ₂ of a diffraction peak at 5 μm appears. Therefore, the uneven strain of the crystal surface layer can be expressed by the value of | v ₁ −v ₂ | which is the difference between v ₁ and v ₂ .

In the nitride crystal of this embodiment, the nonuniform strain of the surface layer represented by the value of | v ₁ −v ₂ | is 150 arcsec or less. By setting the nonuniform strain of the surface layer of the nitride crystal to | v ₁ −v ₂ | ≦ 150 (arcsec), a semiconductor layer having good crystallinity can be epitaxially grown on the nitride crystal, and the characteristics are good. A semiconductor device can be manufactured.

(Embodiment 3)
The nitride crystal of this embodiment has an X-ray penetration of 0.3 μm in a rocking curve measured by changing the X-ray penetration depth from the surface of the crystal with respect to the X-ray diffraction of an arbitrary specific crystal lattice plane of the crystal. The plane of the specific crystal plane represented by the value of | w ₁ −w ₂ | obtained from the half width w ₁ of the diffraction intensity peak at the depth and the half width w ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm. The misorientation is 400 arcsec or less.

Referring to FIG. 1, an X-ray penetration depth of 0.3 μm corresponds to a distance from the surface of the nitride crystal to the crystal surface layer 1a, and an X-ray penetration depth of 5 μm corresponds to the nitride crystal surface from the surface of the nitride crystal 1c. It corresponds to the distance to the inside. At this time, referring to FIG. 5A, the half width w ₂ at the X-ray penetration depth of 5 μm is considered to be the original half width of the crystal, but the half width at the X-ray penetration depth of 0.3 μm. w ₁ reflects the crystal orientation misalignment of the crystal surface layer due to the effect of surface processing of the crystal (for example, the surface orientations of the specific crystal lattice planes 51d, 52d, and 53d of each crystal lattice are different), It takes a value different from the half width w ₂ at the line penetration depth of 5 μm.

In the above case, referring to FIG. 5B, in the rocking curve for any specific crystal lattice plane of the crystal, the half-value width w ₁ at the X-ray penetration depth of 0.3 μm and the X-ray penetration depth of 5 μm. The half width w ₂ appears. Therefore, the deviation of the plane orientation of the specific crystal lattice plane of the crystal surface layer can be expressed by the value of | w ₁ −w ₂ | which is the difference between w ₁ and w ₂ .

In the nitride crystal of the present embodiment, the plane orientation deviation of the specific crystal plane of the surface layer represented by the value | w ₁ −w ₂ | is 400 arcsec or less. By setting the plane orientation shift of the specific crystal plane of the surface layer of the nitride crystal to | w ₁ −w ₂ | ≦ 400 (arcsec), a semiconductor layer with good crystallinity can be epitaxially grown on the nitride crystal. A semiconductor device with good characteristics can be manufactured.

  Note that the crystallinity evaluated by the crystallinity evaluation method in the first to third embodiments is not limited to the one caused by the surface processing described above, and crystal distortion and the like generated during crystal growth are also included. Can be included.

In the nitride crystals of the first to third embodiments, the crystal surface preferably has a surface roughness Ry of 30 nm or less. Here, the surface roughness Ry is extracted from the roughness curved surface by a 10 μm square (10 μm × 10 μm = 100 μm ² , hereinafter the same) as a reference area in the direction of the average surface, and is highest from the average surface of the extracted portion. The sum of the height to the top of the mountain and the depth to the bottom of the lowest valley. By setting the surface roughness Ry of the nitride crystal to 30 nm or less, a semiconductor layer with good crystallinity can be epitaxially grown on the nitride crystal, and a semiconductor device with good characteristics can be obtained.

  In the nitride crystals of the first to third embodiments, the crystal surface preferably has a surface roughness Ra of 3 nm or less. Here, the surface roughness Ra is extracted from the roughness curved surface by a 10 μm square as a reference area in the direction of the average surface, and the absolute value of the deviation from the average surface of the extracted portion to the measurement curved surface is summed up. The value averaged with the reference area. By setting the surface roughness Ra of the nitride crystal to 3 nm or less, a semiconductor layer with good crystallinity can be epitaxially grown on the nitride crystal, and a semiconductor device with good characteristics can be obtained.

  In the nitride crystals of the first to third embodiments, the crystal surface is preferably parallel to the C plane in the wurtzite structure. Here, the C plane means a {0001} plane and a {000-1} plane. A state in which the surface of the group nitride crystal is parallel or nearly parallel to each of the above surfaces in the wurtzite structure (for example, the off-angle that is the angle formed between the surface of the nitride crystal and the C surface in the wurtzite structure is 0. 0). By setting the angle to less than 05 °, a semiconductor layer with good crystallinity can be epitaxially grown on the nitride crystal, and a semiconductor device with good characteristics can be obtained.

  In the nitride crystals of the first to third embodiments, it is preferable that the surface of the crystal has an off angle in the range of 0.05 ° to 15 ° with respect to the C plane in the wurtzite structure. By providing an off angle of 0.05 ° or more, defects in the semiconductor layer epitaxially grown on the nitride crystal can be reduced. However, if the off angle exceeds 15 °, a stepped step is easily formed in the semiconductor layer. From this viewpoint, the off angle is more preferably 0.1 ° or more and 10 ° or less.

(Embodiment 4)
The present embodiment is a nitride crystal substrate formed of the nitride crystals of the first to third embodiments. In addition, by epitaxially growing one or more semiconductor layers on at least one main surface of the nitride crystal substrate of this embodiment, an epitaxial layer including one or more semiconductor layers that are epitaxial layers (also referred to as epilayers) is provided. A nitride crystal substrate is obtained. Here, the relationship between the lattice constant of the nitride crystal substrate (referring to the lattice constant in the axis perpendicular to the crystal growth surface, hereinafter the same in this embodiment) k ₀ and the lattice constant k of the semiconductor layer is expressed as (| k−k _{If 0} | / k) ≦ 0.15, the semiconductor layer can be epitaxially grown on the nitride crystal substrate, and (| k−k ₀ | / k
) ≦ 0.05 is preferable. From this viewpoint, the group III nitride layer is preferable as the semiconductor layer.

(Embodiment 5)
The present embodiment is a semiconductor device including one or more semiconductor layers formed by epitaxial growth on at least one main surface side of the nitride crystal substrate of the fourth embodiment or the nitride crystal substrate with an epi layer. The semiconductor device thus obtained has a nitride crystal substrate or a nitride crystal with an epi layer because at least one of the uniform strain, non-uniform strain and plane orientation deviation of the surface layer of the nitride crystal used as the substrate is small. The semiconductor layer formed on at least one main surface side of the substrate has good crystallinity and good device characteristics can be obtained.

Here, the semiconductor layer in the present embodiment is the same as the semiconductor layer in the fourth embodiment. That is, also in the present embodiment, the relationship between the lattice constant of the nitride crystal substrate (referring to the lattice constant in the axis perpendicular to the crystal growth surface, the same applies to the present embodiment) k ₀ and the lattice constant k of the semiconductor layer is If (| k−k ₀ | / k) ≦ 0.15, the semiconductor layer can be epitaxially grown on the nitride crystal substrate, and (| k−k ₀ | / k) ≦ 0.05. Is preferred. From this viewpoint, the group III nitride layer is preferable as the semiconductor layer.

  Examples of the semiconductor device of the present embodiment include light-emitting elements such as light-emitting diodes and laser diodes, rectifiers, bipolar transistors, field-effect transistors, electronic elements such as HEMTs (High Electron Mobility Transistors), temperature sensors, and pressures. Examples thereof include a sensor, a radiation sensor, a semiconductor sensor such as a visible-ultraviolet light detector, and a SAW device (Surface Acoustic Wave Device).

(Embodiment 6)
Referring to FIG. 6, the semiconductor device of the present embodiment is a semiconductor device including the above-described nitride crystal substrate or the nitride crystal substrate with an epi layer as the substrate 610, and the nitride crystal substrate or the nitride with an epi layer A plurality of three or more semiconductor layers 650 formed by epitaxial growth on one main surface side of the crystal substrate (substrate 610) and the other main layer of the nitride crystal substrate or the nitride crystal substrate with an epi layer (substrate 610). A conductor 682 including a light emitting element including a first electrode 661 formed on the surface side and a second electrode 662 formed on the outermost semiconductor layer of the plurality of semiconductor layers 650, and further mounting the light emitting element. The substrate 610 side of the light emitting element is the light emitting surface side, the outermost semiconductor layer side is the mounting surface side, and the plurality of semiconductor layers 650 include the p-type semiconductor layer 630, the n-type semiconductor layer 620, and their conductivity types Characterized in that it comprises a light-emitting layer 640 formed between the conductive layers. With the above configuration, a semiconductor device having the light emitting surface side on the nitride crystal substrate side can be formed.

  The semiconductor device of this embodiment is excellent in heat dissipation with respect to heat generation in the light emitting layer as compared with the semiconductor device in which the semiconductor layer side is the light emitting surface side. Therefore, even when operated with high power, the temperature rise of the semiconductor device is mitigated and light emission with high luminance can be obtained. In addition, an insulating substrate such as a sapphire substrate needs to have a single-sided electrode structure in which two types of electrodes, an n-side electrode and a p-side electrode, are formed on a semiconductor layer. A double-sided electrode structure in which electrodes are respectively formed on the substrate can be adopted, and most of the main surface of the semiconductor device can be a light emitting surface. Furthermore, there is an advantage that the manufacturing process can be simplified, for example, wire bonding is sufficient for mounting a semiconductor device.

(Embodiment 7)
This embodiment is a semiconductor device including a nitride crystal substrate with an epitaxial layer including a nitride crystal substrate or one or more semiconductor layers formed by epitaxial growth on at least one main surface side of the nitride crystal substrate as a substrate. A method for manufacturing a semiconductor device, comprising: selecting the nitride crystal of Embodiment 1 as a nitride crystal substrate and epitaxially growing one or more semiconductor layers on at least one main surface side of the substrate. is there.

  Since the nitride crystal of Embodiment 1 selected as the nitride crystal substrate of the semiconductor device of this embodiment has a small uniform strain on its surface layer, a semiconductor layer with good crystallinity is epitaxially grown on the nitride crystal. Thus, a semiconductor device with good characteristics can be formed. The semiconductor layer in this embodiment is the same as the semiconductor layer in the fourth and fifth embodiments.

(Embodiment 8)
This embodiment is a semiconductor device including a nitride crystal substrate with an epitaxial layer including a nitride crystal substrate or one or more semiconductor layers formed by epitaxial growth on at least one main surface side of the nitride crystal substrate as a substrate. A method for manufacturing a semiconductor device, comprising: selecting the nitride crystal of Embodiment 2 as a nitride crystal substrate, and epitaxially growing one or more semiconductor layers on at least one main surface side of the substrate. is there.

  The nitride crystal of the second embodiment selected as the nitride crystal substrate of the semiconductor device of the present embodiment has a small nonuniform strain on its surface layer, and therefore a semiconductor layer with good crystallinity is epitaxially grown on the nitride crystal. Therefore, a semiconductor device with good characteristics can be formed. The semiconductor layer in this embodiment is the same as the semiconductor layer in the fourth and fifth embodiments.

(Embodiment 9)
This embodiment is a semiconductor device including a nitride crystal substrate with an epitaxial layer including a nitride crystal substrate or one or more semiconductor layers formed by epitaxial growth on at least one main surface side of the nitride crystal substrate as a substrate. A method for manufacturing a semiconductor device, comprising: selecting the nitride crystal of Embodiment 3 as a nitride crystal substrate, and epitaxially growing one or more semiconductor layers on at least one main surface side of the substrate. is there.

  The nitride crystal of the third embodiment selected as the substrate of the semiconductor device of the present embodiment has a small crystal orientation shift of the specific crystal lattice plane of the surface layer, and thus a semiconductor layer with good crystallinity on the nitride crystal Can be epitaxially grown, and a semiconductor device with good characteristics can be formed. The semiconductor layer in this embodiment is the same as the semiconductor layer in the fourth and fifth embodiments.

  The nitride crystal can be grown by a vapor phase growth method such as an HVPE (hydride vapor phase growth) method or a sublimation method, or a liquid phase growth method such as a flux method.

  A nitride crystal to be a nitride crystal substrate of a semiconductor device is cut out from the nitride crystal obtained by the above growth method, and surface processing such as grinding and polishing is performed to flatten the surface. In surface processing, such as grinding and mechanical polishing, the hard abrasive grains cut into the crystal to remove the material, so the surface of the nitride crystal that becomes the nitride crystal substrate has deteriorated workability due to poor crystallinity. The layer (damage layer) remains. Therefore, in order to produce a high-quality group III nitride semiconductor layer on a substrate flattened by machining, it is necessary to reduce the work-affected layer. CMP processing is most suitable for reducing the work-affected layer from the viewpoint of reducing both the work-affected layer and the surface roughness.

  Note that the work-affected layer on the substrate surface does not need to be completely removed, and the surface can be modified by annealing before epitaxial growth. The crystal surface is rearranged by annealing before growth, and the semiconductor layer having good crystallinity can be epitaxially grown.

As a preferred example of the surface processing method for improving the crystallinity of the surface layer of the nitride crystal, a CMP surface treatment method will be described below. The pH value x and the oxidation-reduction potential value y (mV) of the slurry solution used for CMP are expressed by the following equations (2) and (3).
y ≧ −50x + 1000 (2)
y ≦ −50x + 1900 (3)
It is preferable to satisfy any of these relationships. When y <−50x + 1000, the polishing rate becomes low. On the other hand, if y> -50x + 1900, the corrosive action on the polishing pad and the polishing apparatus becomes large, and stable polishing becomes difficult.

Further, from the viewpoint of further improving the polishing rate, the following formula (4)
y ≧ −50x + 1300 (4)
It is preferable to satisfy this relationship.

  In general, acids such as hydrochloric acid, sulfuric acid, and nitric acid, and alkalis such as KOH and NaOH are added to the CMP slurry, but these acids and / or alkali alone oxidize the surface of chemically stable gallium nitride. The effect to do is small. Therefore, it is preferable to further increase the redox potential by adding an oxidizing agent so as to satisfy the relationship of the above formulas (2) and (3) or the above formulas (3) and (4).

  The oxidizing agent added to the CMP slurry is not particularly limited, but from the viewpoint of increasing the polishing rate, chlorinated isocyanuric acid such as hypochlorous acid and trichloroisocyanuric acid, and chlorinated isocyanuric acid such as sodium dichloroisocyanurate. Salt, permanganate such as potassium permanganate, nichromate such as potassium dichromate, bromate such as potassium bromate, thiosulfate such as sodium thiosulfate, nitric acid, hydrogen peroxide, ozone etc. Preferably used. In addition, these oxidizing agents may be used independently or may use 2 or more together.

  The pH of the CMP slurry is preferably 6 or less or 8 or more. The polishing rate can be increased by bringing an acidic slurry having a pH of 6 or less or a basic slurry having a pH of 8 or more into contact with the group III nitride crystal and etching away the work-affected layer of the group III nitride crystal. . From this viewpoint, the pH of the slurry is more preferably 4 or less or 10 or more.

Here, there are no particular limitations on the acid and base used to adjust the pH of the slurry. For example, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, citric acid, malic acid, tartaric acid, succinic acid In addition to organic acids such as phthalic acid and fumaric acid, bases such as KOH, NaOH, NH ₄ OH and amines, salts such as sulfates, carbonates and phosphates can be used. Moreover, pH can also be adjusted by addition of the said oxidizing agent.

  The CMP slurry preferably contains abrasive grains. The polishing rate can be further increased by the abrasive grains. The abrasive grains included in the slurry are not particularly limited, and are high-hardness abrasive grains whose hardness is higher than that of nitride crystals, low-hardness abrasive grains whose hardness is lower than that of nitride crystals, or high-hardness abrasive grains and low hardness. Mixed abrasive grains with abrasive grains can be used.

(Comparative Example 1)
Using a 500 μm thick Si-doped n-type GaN crystal grown by the HVPE method as a nitride crystal, this n-type GaN crystal was mechanically polished as follows. That is, the Ga side C surface ((0001) surface) of the n-type GaN crystal having a diameter of 50 mm and a thickness of 500 μm is pressed against the surface plate while supplying the slurry in which the diamond abrasive grains are dispersed on the surface plate of the lapping apparatus. Thus, the n-type GaN crystal was mechanically polished. As the surface plate, a copper surface plate or a tin surface plate was used. Three types of abrasive grains having a particle diameter of 6 μm, 3 μm, and 1 μm were prepared, and the grain diameter of the abrasive grains was gradually reduced as the mechanical polishing progressed. The polishing pressure in mechanical polishing was 100 gf / cm ^{2 to} 500 gf / cm ² , and the rotation speed of the surface plate was 30 rpm to 100 rpm.

Next, with respect to the n-type GaN crystal after mechanical polishing, the diffraction X-ray from the (10-13) plane of the wurtzite structure is measured by changing the X-ray penetration depth from 0.3 μm to 5 μm, The interplanar spacing of the (10-13) plane (the specific crystal lattice plane in this measurement) in the diffraction profile, the half width of the diffraction intensity peak, and the half width of the diffraction intensity peak in the rocking curve were determined. For X-ray diffraction measurement, a parallel optical system, CuK _α1 X-ray wavelength was used. The X-ray penetration depth was controlled by changing at least one of the X-ray incident angle ω with respect to the crystal surface, the tilt angle χ of the crystal surface, and the rotation angle φ within the crystal surface. Further, the surface roughness Ry and the surface roughness Ra of the n-type GaN crystal were measured with an AFM (atomic force microscope) (DIMENSION 3100 manufactured by VEECO). The results are summarized in Table 1.

Next, referring to FIG. 6, an n-type GaN layer 621 (dopant: Si) having a thickness of 1 μm as an n-type semiconductor layer 620 is formed on one main surface side of an n-type GaN crystal substrate 610 by MOCVD. And a 150 nm thick n-type Al _0.1 Ga _0.9 N layer 622 (dopant: Si), a light emitting layer 640, a 20 nm thick p-type Al _0.2 Ga _0.8 N layer 631 (dopant: Mg) as a p-type semiconductor layer 630, and A p-type GaN layer 632 (dopant: Mg) having a thickness of 150 nm was sequentially formed to obtain a light-emitting element as a semiconductor device. Here, the light emitting layer 640 is formed by alternately laminating four barrier layers formed of GaN layers having a thickness of 10 nm and three well layers formed of Ga _0.85 In _0.15 N layers having a thickness of 3 nm. A multi-quantum well structure was adopted.

  Next, a 200 nm thick Ti layer, a 1000 nm thick Al layer, a 200 nm thick Ti layer, and a 2000 nm thick Au layer are formed as a first electrode 661 on the other main surface side of the n-type GaN crystal substrate 610. A laminated structure formed of layers was formed and heated in a nitrogen atmosphere to form an n-side electrode having a diameter of 100 μm. On the other hand, as a second electrode 662 on the p-type GaN layer 632, a stacked structure formed of a 4 nm thick Ni layer and a 4 nm thick Au layer is formed and heated in an inert gas atmosphere, A p-side electrode was formed. After the laminated body was chipped into a 400 μm square, the p-side electrode was bonded to the conductor 682 with a solder layer 670 formed of AuSn. Further, the n-side electrode and the conductor 681 were bonded with a wire 690 to obtain a semiconductor device 600 having a structure as a light emitting device. The obtained semiconductor device was mounted in an integrating sphere, a current of 20 mA was injected into the semiconductor device to emit light, and the output of light collected by the integrating sphere was measured. However, no light emission was observed in the semiconductor device of this comparative example. The results are summarized in Table 1.

(Examples 1-7)
A semiconductor device was fabricated in the same manner as in Comparative Example 1 except that CMP was performed under the conditions shown in Table 1 after mechanical polishing and before X-ray diffraction. The optical output of the obtained semiconductor device was measured in the same manner as in Comparative Example 1. The results are summarized in Table 1.

(Comparative Example 2)
Using a 400 μm thick Si-doped n-type AlN crystal grown by sublimation as a nitride crystal, this n-type AlN crystal was mechanically polished in the same manner as in Comparative Example 1.

For the n-type AlN crystal after mechanical polishing, the diffraction X-ray from the (11-22) plane of the wurtzite structure is measured by changing the X-ray penetration depth from 0.3 μm to 5 μm. The interplanar spacing of the (11-22) plane (specific crystal lattice plane in this measurement), the half width of the diffraction intensity peak, and the half width of the diffraction intensity peak in the rocking curve were determined. For X-ray diffraction measurement, a parallel optical system, CuK _α1 X-ray wavelength was used. The X-ray penetration depth was controlled by changing at least one of the X-ray incident angle ω with respect to the crystal surface, the tilt angle χ of the crystal surface, and the rotation angle φ within the crystal surface. Further, the surface roughness Ry and the surface roughness Ra of the n-type AlN crystal were measured by AFM. The results are summarized in Table 2.

  Next, a semiconductor device was fabricated in the same manner as in Comparative Example 1 using the AlN crystal as a substrate. When the optical output of this semiconductor device was measured in the same manner as in Comparative Example 1, no light emission was observed. The results are summarized in Table 2.

(Examples 8 to 10)
A semiconductor device was fabricated in the same manner as in Comparative Example 2 except that CMP was performed under the conditions shown in Table 2 after mechanical polishing and before X-ray diffraction. The light output of the obtained semiconductor device was measured in the same manner as in Comparative Example 2. The results are summarized in Table 2.

As apparent from Table 1 and Table 2, in the X-ray diffraction measurement in which the X-ray penetration depth from the surface of the crystal is changed while satisfying the X-ray diffraction conditions of any specific crystal lattice plane of the crystal, 0. Uniform strain of the surface layer obtained from the interplanar spacing d ₁ of the specific crystal lattice plane at an X-ray penetration depth of 3 μm and the interplanar spacing d ₂ of the specific crystal lattice plane at an X-ray penetration depth of 5 μm | d ₁ -d ₂ | / D ₂ is 2.1 × 10 ⁻³ or less, the half-value width v ₁ of the diffraction intensity peak at an X-ray penetration depth of 0.3 μm, and the half-value width v ₂ of the diffraction intensity peak at an X-ray penetration depth of 5 μm Diffraction at a half-value width w ₁ of the diffraction intensity peak at an X-ray penetration depth of 0.3 μm and a non-uniform strain | v ₁ −v ₂ | Crystal surface obtained from half width w _{2 of} intensity peak An LED, which is a semiconductor device in which a nitride crystal satisfying at least one of the plane orientation deviation | w ₁ -w ₂ | of the layer of at least one of 400 arcsec or less is selected as a nitride crystal substrate, has a high light output. It was.

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

1 nitride crystal, 1a crystal surface layer, 1b crystal surface adjacent layer, 1c inner crystal layer, 1d, 51d, 52d, 53d specific crystal lattice plane, 1s crystal surface, 11 incident X-ray, 12 outgoing X-ray, 21 χ axis, 22 ω axis (2θ axis), 23 φ axis, 30 tensile stress, 600 semiconductor device, 610 substrate, 620 n-type semiconductor layer, 621 n-type GaN layer, 622 n-type Al _0.1 Ga _0.9 N layer, 630 p-type semiconductor layer , 631 p-type Al _0.2 Ga _0.8 N layer, 632 p-type GaN layer, 640 light emitting layer, 650 semiconductor layer, 661 first electrode, 662 second electrode, 670 solder layer, 681, 682 conductor, 690 wire.

Claims (8)

The nitride crystal grown by the vapor phase growth method or the liquid phase growth method is machined and then subjected to chemical mechanical polishing, whereby the crystallinity of the surface layer of the nitride crystal deteriorated by the machining is changed to the chemical mechanical A method for producing a nitride crystal that is improved by polishing,
In the chemical mechanical polishing, using a slurry having a pH of 6 or less or 8 or more,
The improvement in crystallinity of the surface layer of the nitride crystal is based on an X-ray diffraction measurement in which the X-ray penetration depth from the surface of the crystal is changed while satisfying the X-ray diffraction condition of an arbitrary specific crystal lattice plane of the crystal. in spacing of the specific parallel crystal lattice plane obtained, resulting from the spacing d ₂ Metropolitan in the spacing d ₁ and 5μm the X-ray penetration depth of in the X-ray penetration depth of 0.3 [mu] m | d ₁ A method for producing a nitride crystal, wherein the uniform strain of the surface layer of the crystal represented by a value of −d ₂ | / d ₂ is 2.1 × 10 ⁻³ or less. The nitride crystal grown by the vapor phase growth method or the liquid phase growth method is machined and then subjected to chemical mechanical polishing, whereby the crystallinity of the surface layer of the nitride crystal deteriorated by the machining is changed to the chemical mechanical A method for producing a nitride crystal that is improved by polishing,
In the chemical mechanical polishing, using a slurry having a pH of 6 or less or 8 or more,
The improvement in crystallinity of the surface layer of the nitride crystal is based on an X-ray diffraction measurement in which the X-ray penetration depth from the surface of the crystal is changed while satisfying the X-ray diffraction condition of an arbitrary specific crystal lattice plane of the crystal. In the obtained diffraction intensity profile of the specific crystal lattice plane, the half width v ₁ of the diffraction intensity peak at the X-ray penetration depth of 0.3 μm and the half width v ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm. A method for producing a nitride crystal in which the nonuniform strain of the surface layer of the crystal represented by the value of | v ₁ −v ₂ | The nitride crystal grown by the vapor phase growth method or the liquid phase growth method is machined and then subjected to chemical mechanical polishing, whereby the crystallinity of the surface layer of the nitride crystal deteriorated by the machining is changed to the chemical mechanical A method for producing a nitride crystal that is improved by polishing,
In the chemical mechanical polishing, using a slurry having a pH of 6 or less or 8 or more,
The improvement in crystallinity of the surface layer of the nitride crystal is a rocking curve measured by changing the X-ray penetration depth from the surface of the crystal with respect to the X-ray diffraction of any specific crystal lattice plane of the crystal. The value of | w ₁ −w ₂ | obtained from the half width w ₁ of the diffraction intensity peak at the X-ray penetration depth of 0.3 μm and the half width w ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm. A method for producing a nitride crystal in which the plane orientation deviation of the specific crystal plane represented by:   The slurry is selected from the group consisting of hypochlorous acid, chlorinated isocyanuric acid, chlorinated isocyanurate, permanganate, dichromate, bromate, thiosulfate, nitric acid, hydrogen peroxide, and ozone. The method for producing a nitride crystal according to any one of claims 1 to 3, comprising one or more oxidizing agents. A method of manufacturing an epitaxial layer-attached nitride crystal substrate including a nitride crystal substrate,
The nitride crystal substrate is a nitride crystal obtained from an X-ray diffraction measurement in which an X-ray penetration depth from the surface of the crystal is changed while satisfying an X-ray diffraction condition of an arbitrary specific crystal lattice plane of the crystal. in spacing of the specific parallel crystal lattice plane is obtained from the plane spacing d ₂ Metropolitan in the spacing d ₁ and 5μm the X-ray penetration depth of in the X-ray penetration depth of 0.3 [mu] m | d ₁ - a crystal having a uniform distortion of a surface layer of the crystal represented by a value of d ₂ | / d ₂ of 2.1 × 10 ⁻³ or less is selected;
A method for manufacturing a nitride crystal substrate with an epi layer, comprising a step of epitaxially growing one or more semiconductor layers on at least one main surface side of the nitride crystal substrate. A method of manufacturing an epitaxial layer-attached nitride crystal substrate including a nitride crystal substrate,
The nitride crystal substrate is a nitride crystal obtained from an X-ray diffraction measurement in which an X-ray penetration depth from the surface of the crystal is changed while satisfying an X-ray diffraction condition of an arbitrary specific crystal lattice plane of the crystal. In the diffraction intensity profile of the specific crystal lattice plane, the half-value width v ₁ of the diffraction intensity peak at the X-ray penetration depth of 0.3 μm and the half-value width v ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm A crystal having a nonuniform strain of the surface layer of the crystal represented by the value of | v ₁ −v ₂ |
A method for manufacturing a nitride crystal substrate with an epi layer, comprising a step of epitaxially growing one or more semiconductor layers on at least one main surface side of the nitride crystal substrate. A method of manufacturing an epitaxial layer-attached nitride crystal substrate including a nitride crystal substrate,
In the rocking curve measured by changing the X-ray penetration depth from the surface of the crystal with respect to the X-ray diffraction of the nitride crystal substrate, which is a nitride crystal and an arbitrary specific crystal lattice plane of the crystal, 0 The value of | w ₁ −w ₂ | obtained from the half width w ₁ of the diffraction intensity peak at the X-ray penetration depth of 3 μm and the half width w ₂ of the diffraction intensity peak at the X-ray penetration depth of 5 μm. A crystal whose plane orientation deviation of the specific crystal lattice plane represented is 400 arcsec or less,
A method for manufacturing a nitride crystal substrate with an epi layer, comprising a step of epitaxially growing one or more semiconductor layers on at least one main surface side of the nitride crystal substrate. The relationship between the lattice constant k ₀ of the nitride crystal substrate and the lattice constant k of the semiconductor layer is (| k−k ₀ | / k) ≦ 0.15. A method of manufacturing a nitride crystal substrate with an epi layer.

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