Patent ID: 7871905

Claim:
A method for producing semiconductor device, comprising: a first masking step of forming a first mask being open partially on the main face of a first conductive type semiconductor substrate; a second masking step of laminating a second mask having a width narrower than that of the first mask on the surfaces of the remaining portions of the first mask; an etching step of forming trenches by etching the semiconductor portions of the first conductive type semiconductor substrate exposed to the opening portions in the first mask and the opening portions in the second mask; an exposing step of narrowing the width of the first mask by using the second mask, and exposing the semiconductor portions on the surface of the first conductive type semiconductor substrate, remaining without being etched after the etching step; and a layer forming step of epitaxially growing a second conductive type semiconductor layer in the trenches and the semiconductor portions of the first conductive type semiconductor substrate exposed in the exposing step.