| 摘要 |
PURPOSE:To decrease one process in comparison with conventional photolithography processes, by performing low concentration diffusion of an NMOS without making a PMOS. CONSTITUTION:In a PMOS forming region 14, a P<+> diffused layer 7 for a source and drain is formed by, e.g., boron-ion implantation, with a field oxide film 3 and a poly Si gate 6 as masks. Masking is performed by resist 5 having a thickness of about 1mum so that boron does not enter into an NMOS forming region 13. Then, the resist 5 is removed, and thereafter, e.g., phosphorus ions are implanted in order to form low-concentration source and drain of the NMOS with the poly Si gate 6 and the field oxide film 3 as masks. Thus an N<-> diffused layer 8 is formed. Since the masking of the PMOS forming region 14 is not performed, phosphorus is implanted in the P<+> diffused layer 7. Owing to the low concentration diffusion, however, the effect of the P<+> diffused layer 7 on the carrier concentration is negligible. |
