The spacer is preferably tapered and the via may include {HEAD ~ a glue layer} to improve {TAIL ~ the adherence} of the spacer to the dielectric layer 
The spacer is preferably tapered and the via may include { HEAD ~ a glue layer } to improve { TAIL ~ the adherence } of the spacer to the dielectric layer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH