| 摘要 |
PURPOSE:To prevent the decrease in inversion suppressing effect by a method wherein an oxide protective film is formed on the doublelayered structure field oxide film of an MOS semiconductor device. CONSTITUTION:A double-layered structure field oxide film 6, consisting of a field thermally oxide film 2 and a vapor growth oxide film 3, is formed on a P-type Si substrate 1, and an oxide protective Si3N4 film 7 if formed thereon. Then, an opening is provided in an element region by performing an RIE method, and a gate oxide film 4 is formed. Thereupon, as there is an oxide protective film 7, the Si having an uncoupled element in the vapor growth oxide film 3 si not subjected to oxidization even when the gate oxide film is formed. As a result, the decrease in the inversion suppression effect of the double-layered structure field oxide film 6 can be prevented, and the increase in leak current generating between elements can also be prevented. The protective film 7 is removed by performing a CDE method after ions have been implanted in a channel region.
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