| 摘要 |
PURPOSE:To shorten an etching time, by forming the side surface of an erase gate at a specified slant angle, and making the thickness of a polysilicon film, which is deposited on the side surface and the upper part of the erase gate, thin. CONSTITUTION:Polysilicon, which is to become an erase gate 21, is deposited on a field oxide film 3 and a gate oxide film 7, which are formed on a semiconductor substrate 1. Phosphorus or arsenic ions are implanted in the deposited polysilicon. Then patterning is performed by a photolithography technology. The polysilicon, which is to become the erase gate 21, is etched. An etching speed is accelerated at the surface of the polysilicon, in which impurities are implanted and the amorphous state is obtained, and the surface side of the gate 21 is slanted. When the slant angle of the gate 21 is made to be about 30 deg., the thickness of a floating gate 9 of polysilicon, which is deposited through the gate 21 and an insulating film so as to face the gate, can be made thin.
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