| 摘要 |
In a method for forming a semiconductor device having a power MOSFET and a diode, after a gate electrode and n+ type source regions for the power MOSFET and an n+ type region of a poly-Si layer for the diode are formed, an oxide film is formed by thermal oxidation. At that time, accelerated oxidation occurs where an n type impurity is heavily implanted, so that the oxide film becomes thick on the surfaces of the gate electrode, the source regions, and the n+ type region, as compared to the other region. Then, a p type impurity is self-alignedly implanted through the oxide film serving as a mask to form a p+ type contact region for the MOSFET and a p+ type region of the poly-Si layer for the diode.
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