| 摘要 |
PROBLEM TO BE SOLVED: To enable a MOS transistor to be easily optimized in function by a method, wherein a gate electrode and source/drain diffusion layers of a first N channel-type MOS transistor are formed, and then a gate electrode and source /drain diffusion layers of a second N channel-type MOS transistor are formed. SOLUTION: A gate electrode 7 of a first N-channel MOS transistor used for a peripheral circuit is formed, phosphorus ions are implanted into all the surface, and a thermal treatment is carried out to form a first N-type lightly doped diffusion layer 9. Then, a spacer insulating film 11 is formed on the sidewalls of the gate electrode 7 and a polysilicon layer, and an N-type heavily doped diffusion layer 13 is formed in the region of the first N-type lightly doped diffusion layer 9 as it is self-aligned with the gate electrode 7 and spacer insulating film 11. Then, the gate electrode 15 of a second N-channel MOS transistor used for an inner circuit or a memory cell and a polysilicon film are formed, arsenic ions are implanted into the entire surface, and then a thermal treatment is carried out to form a second N-type lightly doped diffused layer 17. |
