Manufacture of vertical mosfet device

Abstract

Abstract PURPOSE:To facilitate setting and control of the depth of a recession and diffusion and prevent the characteristic from decreasing by forming beforehand the recession before a diffusion process for forming a base material area. CONSTITUTION:A recession is made in the surface of a drain area prepared beforehand and masked and then an impurity is introduced and diffused. A polysilicon gate part is formed in the recession in a recession masking process. That is, the impurity is implanted in the surface part of the drain area 1 in an impurity implantation process, however, not under the mask, or in the face of the recession 20, but only in faces on the right and left sides thereof. In the next diffusion process, said impurity diffuses from the right and left faces vertically and horizontally to the slopes 20b of the recession, however, the two diffusion areas (base material areas) hardly join just under the recession. The drain area 1 as a non-diffusion area nearly just under the recession 20 comes in contact with the gate part without interposition, therefore, a channel area 6 extending over the drain area 1 under the base of the recession 20, a source area formed after, and the slopes 20b of the recession is securely formed.

Inventors

• 👤 Katsunori Ueno
• 👤 勝典 上野

Bibliographic Details