said {HEAD ~ sidewall surface} of said main part including a sharply pointed tip end part defined by two crystal surfaces and located at {TAIL ~ a lower side} of an interface between said gate insulation film and said silicon substrate 
said { HEAD ~ sidewall surface } of said main part including a sharply pointed tip end part defined by two crystal surfaces and located at { TAIL ~ a lower side } of an interface between said gate insulation film and said silicon substrate
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 TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH