doping second impurity elements at a second concentration smaller than the first concentration providing n type into the semiconductor layer having {TAIL ~ the first n type impurity region} while passing through {HEAD ~ the portion} of the gate electrode to form a second n type impurity region between the first n type impurity region and a channel forming region 
doping second impurity elements at a second concentration smaller than the first concentration providing n type into the semiconductor layer having { TAIL ~ the first n type impurity region } while passing through { HEAD ~ the portion } of the gate electrode to form a second n type impurity region between the first n type impurity region and a channel forming region
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH