Method of manufacturing a semiconductor device with hydrogen ion intercepting layer

A manufacturing method of a semiconductor device comprising the steps of:

• forming a first insulating oxide film and a second insulating oxide film, which continues to said first insulating oxide film and has a thickness larger than that of said first insulating oxide film, on a semiconductor substrate;
• forming a polysilicon film, which covers said first and second insulating oxide film, on said semiconductor substrate;
• forming a silicon nitride layer in a lowermost layer portion of said polysilicon film by implanting nitrogen ions into said lowermost layer portion of said polysilicon film and then applying a heat treatment thereto;
• patterning said polysilicon film and said silicon nitride layer, for forming a first polysilicon resistance film and a second polysilicon resistance film on said first insulating oxide film and said second insulating oxide film, respectively;
• forming a first electrode connected to said first polysilicon resistance film and a second electrode connected to said second polysilicon resistance film;
• and
• forming an insulating protection film, which covers said first polysilicon resistance film, said second polysilicon resistance film, said first electrode and said second electrode, over said semiconductor substrate.