Group III nitride crystal substrate, epilayer-containing group III nitride crystal substrate, semiconductor device and method of manufacturing the same

1. A group III nitride crystal substrate, wherein,

on a diffraction intensity profile of arbitrary specific parallel crystal lattice planes of said crystal substrate being obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a main surface of said crystal substrate while X-ray diffraction conditions of said specific parallel crystal lattice planes are satisfied,

an irregular distortion at a surface layer of said crystal substrate represented by a value of |v 1 −v 2 | obtained from a half value width v 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 μm and a half value width v 2 of the diffraction intensity peak at said X-ray penetration depth of 5 μm is equal to or lower than 130 arcsec, and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said crystal substrate.

2. A group III nitride crystal substrate, wherein,

on a rocking curve being measured by varying an X-ray penetration depth from a main surface of said crystal substrate in connection with X-ray diffraction of arbitrary specific parallel crystal lattice planes of said crystal substrate,

a plane orientation deviation of said specific parallel crystal lattice planes of a surface layer of said crystal substrate represented by a value of |w 1 −w 2 | obtained from a half value width w 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 μm and a half value width w 2 of the diffraction intensity peak at said X-ray penetration depth of 5 μm is equal to or lower than 350 arcsec, and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said crystal substrate.

3. An epilayer-containing group III nitride crystal substrate comprising at least one semiconductor layer provided by epitaxial growth on a main surface of a group III nitride crystal substrate, wherein, in said group III nitride crystal substrate,

a plane spacing of arbitrary specific parallel crystal lattice planes of said group III nitride crystal substrate being obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from said main surface of said group III nitride crystal substrate while X-ray diffraction conditions of said specific parallel crystal lattice planes of said group III nitride crystal substrate are satisfied,

a uniform distortion at a surface layer of said group III nitride crystal substrate represented by a value of |d 1 −d 2 |/d 2 obtained from a plane spacing d 1 at said X-ray penetration depth of 0.3 μm and a plane spacing d 2 at said X-ray penetration depth of 5 μm is equal to or lower than 1.9×10 −3 , and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said group III nitride crystal substrate.

4. A semiconductor device comprising the epilayer-containing group III nitride crystal substrate, wherein, in said group III nitride crystal substrate, in claim 3 .

5. The semiconductor device according to claim 4 , wherein said semiconductor layer contained in said epilayer-containing group III nitride crystal substrate includes a light emitting layer emitting light having a peak wavelength equal to or more than 430 nm and equal to or less than 550 nm.

6. A method of manufacturing a semiconductor device, comprising the steps of:

preparing a group III nitride crystal substrate, wherein,

a plane spacing of arbitrary specific parallel crystal lattice planes of said crystal substrate being obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a main surface of said crystal substrate while X-ray diffraction conditions of said specific parallel crystal lattice planes of said crystal substrate are satisfied,

a uniform distortion at a surface layer of said crystal substrate represented by a value of |d 1 −d 2 |/d 2 obtained from a plane spacing d 1 at said X-ray penetration depth of 0.3 μm and a plane spacing d 2 at said X-ray penetration depth of 5 μm is equal to or lower than 1.9×10 −3 , and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said crystal substrate; and

epitaxially growing at least one semiconductor layer on said main surface of said crystal substrate, thereby forming an epilayer-containing group III nitride crystal substrate.

7. The method of manufacturing a semiconductor device according to claim 6 , wherein in the step of forming said epilayer-containing group III nitride crystal substrate, said semiconductor layer configured to include a light emitting layer emitting light having a peak wavelength equal to or more than 430 nm and equal to or less than 550 nm.

8. The method of manufacturing a semiconductor device according to claim 6 , wherein said specific parallel crystal lattice planes are not parallel to said main surface, and is parallel to any of (10-10), (10-11), (10-13), (11-20), (11-22), (11-24), (10-1-1), (10-1-3), (11-2-2), and (11-2-4) planes.

9. A method of manufacturing a semiconductor device, comprising the steps of:

preparing a group III nitride crystal substrate, wherein,

on a diffraction intensity profile of arbitrary specific parallel crystal lattice planes of said crystal substrate being obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a main surface of said crystal substrate while X-ray diffraction conditions of said specific parallel crystal lattice planes are satisfied,

an irregular distortion at a surface layer of said crystal substrate represented by a value of |v 1 −v 2 | obtained from a half value width v 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 μm and a half value width v 2 of the diffraction intensity peak at said X-ray penetration depth of 5 μm is equal to or lower than 130 arcsec, and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said crystal substrate; and

epitaxially growing at least one semiconductor layer on said main surface of said crystal substrate, thereby forming an epilayer-containing group III nitride crystal substrate.

10. A method of manufacturing a semiconductor device, comprising the steps of:

preparing a group III nitride crystal substrate, wherein,

on a rocking curve being measured by varying an X-ray penetration depth from a main surface of said crystal substrate in connection with X-ray diffraction of arbitrary specific parallel crystal lattice planes of said crystal substrate,

a plane orientation deviation of said specific parallel crystal lattice planes of a surface layer of said crystal substrate represented by a value of |w 1 −w 2 | obtained from a half value width w 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 μm and a half value width w 2 of the diffraction intensity peak at said X-ray penetration depth of 5 μm is equal to or lower than 350 arcsec, and

said main surface has a plane orientation inclined in a <10-10> direction at an angle equal to or greater than 10° and equal to or smaller than 80° with respect to one of (0001) and (000-1) planes of said crystal substrate; and

forming an epilayer-containing group III nitride crystal substrate by epitaxially growing at least one semiconductor layer on said main surface of said crystal substrate.