doping first impurity elements at {HEAD ~ a first concentration} providing n type into {TAIL ~ the semiconductor layer} using the gate electrode as a mask to form a first n type impurity region 
doping first impurity elements at { HEAD ~ a first concentration } providing n type into { TAIL ~ the semiconductor layer } using the gate electrode as a mask to form a first n type impurity region
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH