For this purpose, step S1 may represent a degassing step, as discussed above, while steps S2 and S3 may represent {HEAD ~ the deposition} of a tantalum based material and {TAIL ~ a copper based material}, respectively 
of
For this purpose , step S1 may represent a degassing step , as discussed above , while steps S2 and S3 may represent { HEAD ~ the deposition } of a tantalum based material and { TAIL ~ a copper based material } , respectively
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH