{HEAD ~ A first layer} of photoresist material is spun onto a substrate surface and is exposed in a desired pattern corresponding to the shape of a final structure, at {TAIL ~ a corresponding cross sectional level} in the structure 
is exposed at
{ HEAD ~ A first layer } of photoresist material is spun onto a substrate surface and is exposed in a desired pattern corresponding to the shape of a final structure , at { TAIL ~ a corresponding cross sectional level } in the structure
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH