| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device which can suppress the occurrence of side etching during formation of an n-type polysilicon gate while preventing boron from punching through a substrate due to the diffusion of boron in a p-type polysilicon gate. SOLUTION: The method for manufacturing a semiconductor device includes a step wherein after P+ ions are implanted into a polysilicon film 7 in an nMOSFET region Rn, a heat treatment is given to diffuse phosphorus into a lower portion of the film 7. This diffusion allows the P concentration on top of the film 7 to be reduced, thereby suppressing the growth of an edge on top of a gate electrode during patterning. Then, after B+ ions are implanted into the film 7 in a pMOSFET region Rp, the film 7 is etched into a gate configuration. Since no heat treatment is given to simultaneously diffuse P and B in the film 7, it can be suppressed that B punches through a semiconductor substrate from the gate electrode.
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