The trenches are then filled with {HEAD ~ semiconductor material} of {TAIL ~ a conductivity type} opposite that of the semiconductor body 
The trenches are then filled with { HEAD ~ semiconductor material } of { TAIL ~ a conductivity type } opposite that of the semiconductor body
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH