| 摘要 |
PURPOSE:To enable the On resistance to be made low by making the depth of the second semiconductor layer large, thereby allowing the width of the channel to be made long. CONSTITUTION:A P-type semiconductor layer 4 is formed by, e.g., heat treatment diffusion of 1,200 deg.C. Since the P-type semiconductor layer 4 uses the overhang of a photoresist 7 as an implantation mask the lateral diffusion length does not extend and is thus short as compared with the longitudinal diffusion length. That is, the thermal diffusion is performed deeply in the lingitudinal direction, preventing the punch-through, and shallowly in the lateral direction so as to narrow the channel length, thereby forming the P-type semiconductor layer 4 shallowly so that a polycrystalline silicon pattern 6a overlaps part of the P-type semiconductor layer 4. The P-type semiconductor layer by this thermal diffusion, which is shallow in the lateral direction, determines the characteristics and performance of this device. |
