| 摘要 |
PURPOSE:To finish a photo-etching process at a time, produce self-matching and improve the accuracy of integration by a method wherein another well is formed using a selected oxide film after forming a well as a mask. CONSTITUTION:A silicon oxide film 13 and a silicon nitride film 14 are made up onto a monocrystalline silicon substrate 12. A window for forming the well such as an N type well is opened according to photo-etching, ions 18 are injected using a silicon nitride film 16 and a resist 17 as masks, and the N type well 19 is made up. A silicon oxide film 20 is built up by selective oxidation. The silicon nitride film 16 is removed, the oxide film under the film 16 is removed, the silicon oxide film 21 is employed as a mask, leaving the film 21 selectively oxidized, ions 22 forming a P type are injected, and the P type well 23 is built up. Thus, a photo-etching process can be finished at a time, the N type well and the P type well are made up in self-matching, and a degree of integration can be improved by 20-30%. |
