Method for manufacturing semiconductor device including etching process of silicon nitride film

A method for manufacturing a semiconductor device comprising:

• forming a conductive layer for a floating gate over a semiconductor layer intervening a gate insulating film therebetween;
• removing the conductive layer selectively using a silicon nitride film having an opening as a mask;
• providing a first injection of arsenic using the silicon nitride film as a mask to form a first diffusion layer on the semiconductor layer located at a position corresponding to the opening;
• removing at least a part of a region where arsenic is included in the silicon nitride film by dry etching;
• and
• removing at least a part of a rest of the silicon nitride film by wet etching.

A method for manufacturing a semiconductor device comprising:

• covering a semiconductor substrate in an element region with a silicon nitride film;
• covering the semiconductor substrate in a different region from the element region with an isolation insulating film;
• injecting arsenic into the isolation insulating film using the silicon nitride film as a mask;
• removing at least a part of a region where arsenic is included in the silicon nitride film by dry etching;
• removing at least a part of a rest of the silicon nitride film by wet etching;
• forming a gate electrode over the semiconductor substrate intervening the gate insulating film therebetween in the element region;
• forming an impurity diffusion region which will be a source and drain on the semiconductor substrate in the element region;
• forming a metallic film over the entire surface;
• and
• performing a heat treatment to form a silicide layer by reacting the surface of the impurity diffusion region with the metallic film.