{HEAD ~ a pair} of {TAIL ~ SiGe mixed crystal regions} formed in said silicon substrate at respective outer sides of said source extension region and said drain extension region when viewed from said channel region, 
{ HEAD ~ a pair } of { TAIL ~ SiGe mixed crystal regions } formed in said silicon substrate at respective outer sides of said source extension region and said drain extension region when viewed from said channel region ,
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH