The method 12, wherein the boron doped region is formed by {TAIL ~ solid state diffusion} and {HEAD ~ etching} 
The method 12 , wherein the boron doped region is formed by { TAIL ~ solid state diffusion } and { HEAD ~ etching }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD