| 摘要 |
PURPOSE:To achieve formation of nitride film without deteriorating electrical characteristic of an element, by conducting the nitride bilm forming process by allowing an oxide film to exist between an Si substrate and an Si3N4 film. CONSTITUTION:A window is opened on an oxide film 22 formed on an Si substrate 21 and PSG23 is put on the film 22, and thickness of the film 23 is to be approximately 200Angstrom so that the Si substrate would not be affected at the time of the nitride film forming process. And then, a nitride film 24 is piled to such a thickness as to achieve chemical formation (approximately 300Angstrom , etc.). Anodic treatment is executed to anodize the nitride film. The PSG23 is provided to a thickness below 500Angstrom and current required for formation is made to pass. Finally, thus formed oxide membrane 25 and the PSG23 below are etched out by HF type liquid. As, in this structure, the PSG23 provides the Si substrae 21 with a protective film against formation of the nitride film 24, formation of a diffusion layer 26 does not occur, the joining depth is not changed, and the surface is not roughened. And therefore, deterioration of dielectric strength and increase of leak, etc. would not occur. |
