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