Patent ID: 7303946

Claim:
A method of manufacturing a semiconductor device comprising the steps of: forming an insulating film containing silicon and nitrogen on a semiconductor substrate; forming a film which must be processed and which contains silicon on the insulating film; processing the film which must be processed to cause a portion of the insulating film to be exposed to the outside; and lowering a surface of the semiconductor substrate under a part of the insulating film relative to a surface of the semiconductor substrate under the film which is processed to cause the portion of the insulating film to be exposed to the outside by applying a thermal oxidation process to a semiconductor structure obtained owing to the above steps, the thermal oxidation process using an oxidizing gas containing one of ozone and oxygen radicals, the oxygen radicals being generated by remote plasma oxidizing method or by reacting a first gas containing oxygen and a second gas containing hydrogen, and a concentration of nitrogen of the part of the insulating film under an edge portion of the film being decreased by the thermal oxidation process.