Patent ID: 7176520

Claim:
A semiconductor device including a MOSFET comprising: a source and a drain formed over a portion of the main surface of a semiconductor substrate of a first conductivity type, the source and drain each having a second conductivity type which is opposite to the first conductivity type; a well of the first conductivity type formed under the source; a gate electrode formed over the main surface of the semiconductor substrate via a gate insulating film; sidewall spacers formed over the sidewalls of the gate electrode; a source rear electrode formed on a back surface of the semiconductor substrate; and a sinker layer of the first conductivity type electrically connecting the source and the source rear electrode, wherein the drain comprises a lightly doped drain region and a heavily doped drain region formed in contact with the lightly doped drain region, the heavily doped drain region having a higher impurity concentration than that of the lightly doped drain region, wherein the lightly doped drain region is comprised of a first lightly doped drain region and a second lightly doped drain region; wherein the second lightly doped drain region has an impurity concentration higher than that of the first lightly doped drain region; and wherein the second lightly doped drain region is located between the first lightly doped drain region and heavily doped drain region.