Patent ID: 7223646

Claim:
A manufacturing method of a semiconductor device comprising the processes of: introducing the first impurities of the first conductivity type into the semiconductor region of a semiconductor substrate, and activating said first impurity; forming a thin semiconductor film on said semiconductor region; amorphizing said semiconductor region to a predetermined depth from said semiconductor film; patterning a gate electrode on said amorphized semiconductor film through a gate insulator; introducing the second impurities of the second conductivity type into the semiconductor region from said semiconductor film at both sides of said gate electrode, and forming a source region and a drain region; activating said second impurity introduced, and recrystallizing the amorphized portion of said semiconductor film and said semiconductor region, by performing heat treatment, wherein said semiconductor film in the channel region is substantially not containing impurities and formed so that the concentration of said first impurity increases in a steep, step-wise manner at the interface between said semiconductor film and the semiconductor region of the semiconductor substrate, and the steep, step-wise manner is maintained.