Patent ID: 8664031

Claim:
A process for making a semiconductor device including a semiconductor photodiode region specifically configured for receiving light with a wavelength of 500 nm or less, the process comprising: providing a silicon substrate of a first conductivity type having therein a region of a second conductivity type with a light receiving area of a semiconductor photodiode at a light receiving surface of the substrate; forming an interlayer insulating layer on the light receiving surface of the silicon substrate with an opening over the light receiving area of the semiconductor photodiode; forming an antireflection film in the opening over the light receiving area, said antireflection film including a silicon oxide film and a silicon nitride film, said antireflection film being formed by first thermally oxidizing silicon on a surface of the silicon substrate in an atmosphere of oxygen gas or in an atmosphere of mixed gas of oxygen and hydrogen at a temperature of 800° C. or more in a state in which at least said surface of the silicon substrate serving as a light-receiving portion of the region is exposed and then depositing a silicon nitride film on said silicon oxide film, wherein, at least said silicon oxide film and said silicon nitride film are left on the surface of said photodiode region in the light receiving area as said antireflection film following the process, said antireflection film overlies said entire opening; said antireflection film has a reflectance periodicity defined by its thickness, said silicon oxide film is formed to have a thickness of at most 50 nm, and said silicon nitride film is formed to have a least thickness that produces the least reflectance.