Semiconductor device and method of manufacturing the same

Abstract

A first MISFET which is a semiconductor element is formed on an SOI substrate. The SOI substrate includes a supporting substrate which is a base, BOX layer which is an insulating layer formed on a main surface (surface) of the supporting substrate, that is, a buried oxide film; and an SOI layer which is a semiconductor layer formed on the BOX layer. The first MISFET as a semiconductor element is formed to the SOI layer. In an isolation region, an isolation groove is formed penetrating though the SOI layer and the BOX layer so that a bottom surface of the groove is positioned in the middle of a thickness of the supporting substrate. An isolation film is buried in the isolation groove being formed. Then, an oxidation resistant film is interposed between the BOX layer and the isolation film.

1 - 10 . (canceled) 
     
     
         11 . A method of manufacturing a semiconductor device comprising the steps of:
 (a) preparing a semiconductor substrate including a base, an insulating layer on the base, and a semiconductor layer on the insulating layer;   (b) forming a groove by etching the semiconductor layer, the insulating layer, and the base in an isolation region;   (c) forming a concave portion to a side surface of the groove by etching a portion of the insulating layer exposed to the side surface of the groove;   (d) forming an oxidation resistant film so as to fill the concave portion and also cover the side surface of the groove;   (e) etching the oxidation resistant film so as to leave the oxidation resistant film in the concave portion; and   (f) forming an isolation film so as to fill the groove.   
     
     
         12 . The method of manufacturing a semiconductor device according to  claim 11 ,
 wherein the insulating layer and the isolation film each include a silicon oxide film.   
     
     
         13 . The semiconductor device according to  claim 12 ,
 wherein the oxidation resistant film includes a silicon nitride film.   
     
     
         14 . The method of manufacturing a semiconductor device according to  claim 11 , further comprising the step of
 (g) polishing the isolation film being formed.