Nitride crystal, nitride crystal substrate, epilayer-containing nitride crystal substrate, semiconductor device and method of manufacturing the same
A nitride crystal is characterized in that, in connection with plane spacing of arbitrary specific parallel crystal lattice planes of the nitride crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of the crystal while X-ray diffraction conditions of the specific parallel crystal lattice planes are satisfied, a uniform distortion at a surface layer of the crystal represented by a value of |d 1 −d 2 |/d 2 obtained from the plane spacing d 1 at the X-ray penetration depth of 0.3 μm and the plane spacing d 2 at the X-ray penetration depth of 5 μm is equal to or lower than 2.1×10 −3 . The above configuration provides the nitride crystal having a crystal surface layer that is evaluated directly and reliably without breaking the crystal so that it can be used in a preferred fashion as a substrate for a semiconductor device as well as the nitride crystal substrate, an epilayer-containing nitride crystal substrate, a semiconductor device and a method of manufacturing the same.
1. An n-type nitride crystal, wherein,
in connection with plane spacing of arbitrary specific parallel crystal lattice planes of the nitride crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while X-ray diffraction conditions of said specific parallel crystal lattice planes being satisfied, a uniform distortion at a surface layer of said crystal represented by a value of |d 1 −d 2 |/d 2 obtained from said plane spacing d 1 at said X-ray penetration depth of 0.3 μm and said plane spacing d 2 at the X-ray penetration depth of 5 μm is equal to or lower than 2.1×10 −3 .
2. An n-type nitride crystal, wherein,
on a diffraction intensity profile of arbitrary specific parallel crystal lattice planes of the nitride crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while X-ray diffraction conditions of said specific parallel crystal lattice planes being satisfied, an irregular distortion at a surface layer of said crystal 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 150 arcsec.
3. An n-type nitride crystal, wherein,
on a rocking curve measured by varying an X-ray penetration depth from a surface of the nitride crystal in connection with X-ray diffraction of arbitrary specific parallel crystal lattice planes of said crystal, a plane orientation deviation of said specific parallel crystal lattice planes 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 400 arcsec.
4. The n-type nitride crystal according to claim 2 , wherein
said surface of said crystal has a surface roughness Ry of 30 nm or lower.
5. The n-type nitride crystal according to claim 2 , wherein
said surface of said crystal has a surface roughness Ra of 3 nm or lower.
6. The n-type nitride crystal according to claim 2 , wherein
said surface of said nitride crystal is parallel to a C-plane of a wurtzite structure.
7. The n-type nitride crystal according to claim 2 , wherein
said surface of said nitride crystal has an off angle in a range from 0.05° to 15° with respect to a C-plane of a wurtzite structure.
8. A Si-doped nitride crystal substrate formed of the n-type nitride crystal according to claim 2 , wherein said n-type nitride crystal is an Si-doped nitride crystal.