| 摘要 |
PURPOSE:To obtain the titled device improved in characteristics by the removal of lamination defects formed in the neighborhood of the surface by including the process of heat-treating a semiconductor substrate at 1,100 deg.C or more and the process of removing the surface layer of the substrate to a depth of 0.5mum or more. CONSTITUTION:When an Si substrate is heat-treated at 1,200 deg.C for 10hr in an oxidizing atmosphere, a layer 11 of low oxygen concentration is produced. At the same time, a thin SiO2 film is formed and lamination defects 5 generate thereunder. Next, on heat treatment at 600-700 deg.C for about 30hr and then at 1,100 deg.C for 20hr, crystal defects 2 having the IG effect are formed inside with high density. The lamination defect 5 caused by heat treatment can be removed almost perfectly by etching said layer 11 bt approx. 10% thickness. Therefore, in formation of an MOS transistor, it is sufficient that the surface of said layer 11 of 4-5mum thickness in etched by 0.5mum after formation of this layer. Then, leakage current, dark current, etc. reduce, and both of reliability and manufacturing yield improve. |
