There are disclosed TFTs having improved reliability. An interlayer dielectric film forming the TFTs is made of a silicon nitride film. Other interlayer dielectric films are also made of silicon nitride. The stresses inside the silicon nitride films forming these interlayer dielectric films are set between −5×109 and 5×109 dyn/cm2. This can suppress peeling of the interlayer dielectric films and difficulties in forming contact holes. Furthermore, release of hydrogen from the active layer can be suppressed. In this way, highly reliable TFTs can be obtained.