providing {HEAD ~ another ion implantation mask} which exposes {TAIL ~ a portion} of the source/base region; and 
exposes
providing { HEAD ~ another ion implantation mask } which exposes { TAIL ~ a portion } of the source / base region ; and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH