Nitride semiconductor substrate, semiconductor device, and methods for manufacturing nitride semiconductor substrate and semiconductor device
A nitride semiconductor substrate having a main surface serving as a semipolar plane and provided with a chamfered portion capable of effectively preventing cracking and chipping, a semiconductor device fabricated using the nitride semiconductor substrate, and a method for manufacturing the nitride semiconductor substrate and the semiconductor device are provided. The nitride semiconductor substrate includes a main surface inclined at an angle of 71° or more and 79° or less with respect to the (0001) plane toward the [1-100] direction or inclined at an angle of 71° or more and 79° or less with respect to the (000-1) plane toward the [−1100] direction; and a chamfered portion located at an edge of an outer periphery of the main surface. The chamfered portion is inclined at an angle θ 1 or θ 2 of 5° or more and 45° or less with respect to adjacent one of the main surface and a backside surface on a side opposite to the main surface. Accordingly, cracking and chipping occurring from the edge of the outer periphery of the nitride semiconductor substrate can be effectively suppressed.
1. A nitride semiconductor substrate comprising:
a main surface inclined at an angle of 71° or more and 79° or less with respect to a (0001) plane toward a [1-100] direction or inclined at an angle of 71° or more and 79° or less with respect to a (000-1) plane toward a [−1100] direction; and
a chamfered portion located at an edge of an outer periphery of said main surface,
said chamfered portion being inclined at an angle of 5° or more and 45° or less with respect to adjacent one of said main surface and a backside surface on a side opposite to said main surface,
said chamfered portion includes a topside chamfer formed on the main surface side and a backside chamfer formed on the backside surface side, and
a damaged layer formed in the topside chamfer has a thickness greater than that of a damaged layer formed in the backside chamfer.
2. The nitride semiconductor substrate according to claim 1 , wherein a damaged layer having an average thickness of 0.5 μm or more and 10 μm or less is formed on a surface layer of said chamfered portion.
3. The nitride semiconductor substrate according to claim 1 , wherein a chamfering amount of said chamfered portion is 0.02 mm or more and 0.5 mm or less.
4. The nitride semiconductor substrate according to claim 1 , wherein a surface roughness of said chamfered portion is 0.07 μm or more and 3 μm or less in terms of Ra.
5. A semiconductor device fabricated using the nitride semiconductor substrate according to claim 1 .