| 摘要 |
PURPOSE:To form a thick surface oxide film on a high withstanding-voltage element part and to form a thin oxide film at a low withstanding-voltage element part, by using a selective oxidation method, with a silicon nitride film as a mask. CONSTITUTION:On the exposed surface of single crystal silicon islands 1 and 2 for a high withstanding-voltage element and a low withstanding-voltage element, a silicon oxide film 3 and a silicon nitride film 3a are formed. Then the film 3a is selectively etched, and a silicon oxide film 3b at a part, which is contacted with a high-concentration embedded layer 7 in the island 1, is exposed. Then, with the film 3a as a mask, the surface of a substrate is selectively oxidized. The exposed film 3 and 3a are thickly formed. Then the film 3a is removed, impurities are diffused and an impurity diffused region 9 is formed. Thereafter a metal wiring 8 is provided. |
