Patent ID: 11970784
Assignee: SUMITOMO CHEMICAL COMPANY LIMITED
Field: Semiconductors (Electrical engineering)
Classification: CPC C  H | IPC C

Claim 8:
9. A method for manufacturing a nitride semiconductor substrate, which is a method for manufacturing a nitride semiconductor substrate with a vapor deposition method, comprising:
a step of preparing a base substrate comprising a single crystal of a group III nitride semiconductor, and having a mirror main surface whose closest low index plane is a (0001) plane;
an initial step of epitaxially growing a single crystal of a group III nitride semiconductor with the (0001) plane as a growth surface directly on the main surface of the base substrate to grow an initial layer;
a first step of epitaxially growing a single crystal of a group III nitride semiconductor having a top surface with the (0001) plane exposed on the initial layer, forming a plurality of concaves composed of inclined interfaces other than the (0001) plane on the top surface, gradually expanding the inclined interfaces toward an upper side of the initial layer, making the (0001) plane disappear from the top surface, and growing a first layer whose surface is composed only of the inclined interfaces; and
a second step of epitaxially growing a single crystal of a group III nitride semiconductor on the first layer, making the inclined interfaces disappear, and growing a second layer having a mirror surface,
wherein a growth rate of the initial layer in the initial step is lower than a growth rate of the first layer in the first step, and
in the first step, a plurality of valleys and a plurality of tops are formed on the surface of the first layer by forming the plurality of concaves on the top surface of the single crystal and making the (0001) plane disappear, and
when observing an arbitrary cross section perpendicular to the main surface,
an average distance between a pair of tops separated in a direction along the main surface is more than 100 μm, the pair of tops being closest to each other among the plurality of tops, with one of the plurality of valleys sandwiched between them.