The method 13, wherein said forming the back gate area includes introducing an impurity of {TAIL ~ the second conductivity type} into the surface of the first region and the portion below {HEAD ~ the recessed portion} of the gate electrode using the gate electrode as a mask 
The method 13 , wherein said forming the back gate area includes introducing an impurity of { TAIL ~ the second conductivity type } into the surface of the first region and the portion below { HEAD ~ the recessed portion } of the gate electrode using the gate electrode as a mask
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH