The present invention proposes a semiconductor device, its manufacturing method and to an electronic apparatus thereof equipped with the semiconductor device where it becomes possible to make a CMOS type solid-state imaging device, an imager area formed with a MOS transistor of an LDD structure without having a metal silicide layer of a refractory metal, an area of DRAM cells and the like into a single semiconductor chip. According to the present invention, a semiconductor device is constituted such that an insulating film having a plurality of layers is used, sidewalls at the gate electrodes are formed by etching back the insulating film of the plurality of layers or a single layer film in the region where metal silicide layers are formed and in the region where the metal silicide layers are not formed, sidewalls composed of an upper layer insulating film is formed on a lower layer insulating film whose surface is coated or the insulating film of the plurality of layers remain unchanged.