| 摘要 |
PROBLEM TO BE SOLVED: To reduce the operation voltage of a memory cell by preventing a thick oxide film from being formed on the side surface of a floating gate electrode, when forming an insulation film between the floating gate electrode and a control gate electrode. SOLUTION: A field oxide film 10 is formed and a buffer oxide film is etched. A resist mask is formed and arsenic atoms are injected. The resist mask is eliminated, and an impurity element is diffused. Thermal oxidation is made, and an increased speed oxide film 53 is formed at the part where arsenic is injected. A tunnel oxide film is formed, and a polysilicon layer is etched. A polysilicon layer 56 for control gate electrode is deposited, and a high- temperature oxide film is deposited. A resist pattern 57 is formed, and the polysilicon layer 56 for control gate electrode is subjected to etching machining. An insulation film ONO film 17 is etched. A polysilicon layer 12 for floating gate electrode is etched in self-alignedly, thus forming a floating gate electrode and hence achieving low-voltage operation.
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