| 摘要 |
PURPOSE:To reduce the number of processes and manufacture a low cost power- MOSFET by simultaneously performing diffusion for forming a second conductivity type well and diffusion for forming a second conductivity type channel region. CONSTITUTION:By photo process, a poly-Si film 5 and a gate oxide film 4 are selectively etched; windows 5A and 4A wider than the exposed surface of a P<+> type well 3 to be formed in the later process are formed in the poly-Si film 5 and the gate oxide film 4; comparatively low dosage of boron ion for forming a channel region 6 is implanted via the windows 5A and 4A; resist 13 is formed by photo process; by using the resist 13 as a mask, high dosage of boron ion is implanted in a region narrower than the windows 5A and 4A; after that, diffusion processes for two times ion implantations are commonly performed, and the P-type channel region 6 and the P<+> type well 3 are simultaneously formed. Thereby the process for forming the P<+> type well can be omitted, and a power-MOSFET of low cost can be realized. |
