Patent ID: 8211811

Claim:
A method for manufacturing a semiconductor device, further comprising: forming a first insulating film; forming an amorphous silicon layer on the first insulating film by supplying a silicon containing gas in an atmosphere at a first temperature of 550° C. or lower; forming a first silicon nitride layer on the amorphous silicon layer and diffusing nitrogen to the amorphous silicon layer by supplying the silicon containing gas, and supplying a nitriding gas while maintaining the atmosphere at the first temperature; forming a second silicon nitride layer on the first silicon nitride layer and diffusing nitrogen to the amorphous silicon layer by increasing the temperature of the atmosphere from the first temperature to a second temperature and maintaining the atmosphere at the second temperature; forming a third silicon nitride layer on the second silicon nitride layer and diffusing nitrogen to the amorphous silicon layer by stopping supplying the silicon containing gas and keep supplying the nitriding gas while maintaining the atmosphere at the second temperature; and forming a second insulating film above the third silicon nitride layer.