Subsequent layers are spun onto the top surface of prior layers and exposed, and upon {TAIL ~ completion} of the succession of layers each defining corresponding levels of the desired structure, the layers are all developed at the same time leaving {HEAD ~ the three dimensional structure} 
Subsequent layers are spun onto the top surface of prior layers and exposed , and upon { TAIL ~ completion } of the succession of layers each defining corresponding levels of the desired structure , the layers are all developed at the same time leaving { HEAD ~ the three dimensional structure }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH 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 HEAD HEAD