Patent ID: 8119545

Claim:
A process for producing a silicon nitride film that introduces microwaves into a treatment vessel via a planar antenna having a plurality of holes to generate plasma using a plasma CVD apparatus and forms the silicon nitride film on an object to be treated by a plasma CVD method, the process comprising: setting a treatment pressure to be constant in a range from 0.1 Pa to 1333 Pa using a film forming gas including a silicon-containing compound gas and either one of nitrogen gas and ammonia gas; when the film forming gas includes nitrogen gas, selecting at least two flow ratios of the silicon-containing compound gas to nitrogen gas (silicon-containing compound gas/nitrogen gas) in the range of 0.005 and 0.2 while keeping the treatment pressure constant; when the film forming gas includes ammonia gas, selecting at least two flow ratios of the silicon-containing compound gas to ammonia gas (silicon-containing compound gas/ammonia gas) in the range of 0.015 and 0.2 while keeping the treatment pressure constant; and forming the silicon nitride film having at least two regions each having a band gap in the range of 2.5 eV and 7 eV by performing the plasma CVD method, wherein the band gap of the silicon nitride film in each of the at least two regions is different from each other by at least 0.3 eV.