Process Window Centering for 22 nm lithography

PWC (Process Window Centering) is an efficient methodology to validate or adjust and center the overall process window for a particular lithography layer by detecting systematic and random defects. The PWC methodology incorporates a defect inspection and analysis of the entire die that can be automated to provide timely results. This makes it a good compromise between FEM (Focus Exposure Matrix), where centering is based only on CD (critical dimension) measurements of a few specific structures and PWQ (Process Window Qualification) which provides very detailed defect inspection and analysis, but is more time consuming for lithography centering. This paper describes the application of the PWC methodology for 22 nm lithography centering in IBM's Albany and East Fishkill development facilities using KLA-Tencor's 28xx brightfield defect inspection system.