| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device where a semiconductor substrate is prevented from being etched, due to overetching at patterning a gate electrode and the desired characteristics can be obtained, and to provide a manufacture method thereof. SOLUTION: A gate insulating film 2 is formed on a silicon substrate 1, and the polycrystalline silicon layer 3 of structure containing an oxygen leak layer 5 is formed on the gate insulating film 2. The polycrystalline silicon layer 3 is formed of a lower polycrystalline silicon layer 4, an oxygen leakage layer 5 and an upper polycrystalline silicon layer 6. The upper polycrystalline silicon layer 6, except for a gate electrode pattern on the upper side from the oxygen leakage layer 5, is removed through reactive ion etching. An oxide silicon film is formed by oxidizing the surfaces of the lower polycrystalline silicon layer 4 and the upper polycrystalline silicon layer 6, which lie above the gate insulating film 2. Then, the oxide silicon film is removed through isotropic etching, and the gate insulating film 2 is exposed.
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