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