Masking plates 52, fabricated of metal, are positioned across {HEAD ~ aperture} 46 of {TAIL ~ plate} 40 an equal distance from the center of the aperture to prevent deposition of charge over a ringed shaped portion of the wafer 
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Masking plates 52 , fabricated of metal , are positioned across { HEAD ~ aperture } 46 of { TAIL ~ plate } 40 an equal distance from the center of the aperture to prevent deposition of charge over a ringed shaped portion of the wafer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL 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