Semiconductor device and manufacturing method of the same

摘要

Source/drain diffusion regions are formed at a surface of a silicon substrate, which is substantially flat and has a first surface roughness. Surfaces of the source/drain diffusion regions are covered with a polysilicon film having a surface which has a second surface roughness larger than the first surface roughness. The polysilicon film is removed by etching to expose the surfaces of the source/drain diffusion regions. Owing to this etching for removal, the surfaces of the source/drain diffusion regions have a third surface roughness larger than the first surface roughness.