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