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