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