Preferably {TAIL ~ the ARC mask} consists of a first layer of between 300 and 1500 angstroms of silicon rich silicon nitride having {HEAD ~ an extinction coefficient} of from 0.77 to 1.07, and a second layer of between 170 and 320 angstroms of silicon oxynitride having an extinction coefficient of about 0.32 
Preferably { TAIL ~ the ARC mask } consists of a first layer of between 300 and 1500 angstroms of silicon rich silicon nitride having { HEAD ~ an extinction coefficient } of from 0.77 to 1.07 , and a second layer of between 170 and 320 angstroms of silicon oxynitride having an extinction coefficient of about 0.32
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH