| 摘要 |
PURPOSE: To realize a semiconductor device having ONO type insulating film of high breakdown strength by a method wherein the ONO type gate insulating film is reformed by thermal oxidizing an SiO2 film of the third layer formed by CVD process meeting specific requirements. CONSTITUTION: In the three layer structured insulating film 14, after the formation of the first layer SiO2 film 16 by thermal oxidizing process of a silicon substrate 10, the second layer SiN layer 18 and the third SiO2 layer are successively formed by CVD process to be maintained in oxygen atmosphere meeting the temperature requirement at 800 deg.C-1150 deg.C for 0.5-5 minutes for thermal oxidizing the third layer. Next, a gate electrode 22 mad of polysilicon 22a and WSix film 22b is formed and ion-implanted to form source/drain regions further to form an interlayer insulating film 24 for making a contact hole 26 on the source/ drain region. Accordingly, by forming a wiring layer 28 and an electrode 30 after heat treatment, the breakdown strength characteristics can be enhanced by the reformation not adversely affecting the underlying layer of the ONO structure insulating film. |
