Patent ID: 11949007
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A semiconductor device comprising:
a semiconductor substrate with a first main surface and a second main surface;
a drift layer of a first conductivity type formed in the semiconductor substrate;
an impurity diffusion layer of a second conductivity type formed on the drift layer to be closer to the first main surface; and
a buffer layer of the first conductivity type formed on the drift layer to be closer to the second main surface and higher in peak impurity concentration than the drift layer,
the buffer layer comprising:
a first buffer layer absent a lattice defect providing a trap level; and
a second buffer layer provided between the first buffer layer and the drift layer and including a lattice defect providing two types of trap levels.