| 摘要 |
PURPOSE:To obtain an FET having a high withstanding voltage without increasing a threshold voltage, by isolating the overlapped part of a gate, a source and a drain by an oxide film. CONSTITUTION:A nitride film 217 is applied on a thermal oxide film 215 on an N-type Si substrate 211, and oxidation is performed. Thus an oxide film 219, which has a thickness of about three times the film 215 is formed, and the mask 217 is removed. Then,a poly Si gate electrode 215 is formed by a CVD method. With the electrode 216 as a mask, RIE of the gate oxide film 219 is carried out. P-type impurity diffused layers 213A (source S) and 213B (drain D) are formed. Since the concentration of electrolysis at the time of operation is alleviated by the presence of the thick oxide film 219, the withstanding voltage in the P-N junction is increased.
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