| 摘要 |
PURPOSE: To protect a semiconductor device against defects induced in a LOCOS oxidation process where a groove is formed or in a following thermal treatment. CONSTITUTION: An N<+> -type semiconductor substrate 1 is doped with impurities of As as high in dose as 1×10<19> cm<-3> (1), and a semiconductor layer 2 is set lower than the N<+> -type semiconductor substrate 1 in impurity concentration (2). By the effect of (1) and (2), defects (× marks 20) caused by crystal strain which is induced by a high-impurity concentration of the N<+> -type semiconductor substrate 1 are generated, and defects (× marks 21) caused by crystal strain which is induced by an impurity concentration difference between the N<+> -type semiconductor substrate 1 and the N<-> - type semiconductor layer 2 are generated in the vicinity of a boundary between the substrate 1 and the layer 2. The defects 20 and 21 absorb harmful impurity contaminant absorbed into the semiconductor substrate 1 and the semiconductor layer 2 in a wafer forming process to lessen harmful impurity contaminant present in the vicinity of a groove provided to the surface of the semiconductor layer 2. In result, defects are restrained from occurring in the vicinity of groove, and a leakage failure and a dielectric strength failure which occur between a drain electrode 11 and a source electrode 9 accompanying defects induced in a channel region are prevented. |
