Therefore, it is possible to process {HEAD ~ the peripheral part} of {TAIL ~ the substrate} without processing the central portion of the substrate 
of
Therefore , it is possible to process { HEAD ~ the peripheral part } of { TAIL ~ the substrate } without processing the central portion of the substrate
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH