Patent ID: 11908688
Assignee: SUMITOMO CHEMICAL COMPANY LIMITED
Field: Semiconductors (Electrical engineering)
Classification: CPC H  C | IPC H

Claim 7:
8. A laminated structure, comprising:
a base substrate comprising a single crystal of a group III nitride semiconductor and having a main surface whose closest low index crystal plane is a (0001) plane;
a mask layer provided on the main surface of the base substrate and having a plurality of openings;
a first low oxygen concentration region provided on the main surface of the base substrate through the openings of the mask layer and on the mask layer and comprising a single crystal of a group III nitride semiconductor;
a high oxygen concentration region provided on the first low oxygen concentration region and comprising a single crystal of a group III nitride semiconductor; and
a second low oxygen concentration region provided on the high oxygen concentration region and comprising a single crystal of a group III nitride semiconductor,
wherein an oxygen concentration in the high oxygen concentration region is higher than an oxygen concentration in each of the first low oxygen concentration region and the second low oxygen concentration region, and
observation of an arbitrary cross section perpendicular to the main surface reveals that,
a top surface of the first low oxygen concentration region includes at least one valley and a plurality of tops at an upper side of each of the plurality of openings of the mask layer, and
an average distance between a pair of mountains separated in a direction along the main surface is more than 100 μm, the pair of mountains being closest to each other among the plurality of mountains, with one valley sandwiched between them.