Lubrication in Photolithography Resist Protect Coats

Defects in photolithographic processing account for large yield losses in semiconductor device fabrication. A major factor contributing to these defects is pinholes formed by photoresist pieces pulled from the resisted layer with subsequent undesired etching of oxide, metal, or passivation glass during processing. Further, for negative photoresist, pieces on the mask "print" during exposure forming latent defects which etch during processing also giving shorts, parted metal, and the like. Using surface chemical principles of lubrication, a resist protect coat (RPC) formulation based on polyvinyl al-cohol, a surfactant, and a lubricant has been developed which greatly mini-mizes these defects. Significant increases in effective mask use and increased yields for three layer metal devices are shown. It is well known that repeated mask-wafer contacts in semiconductor photolithography severely deteriorate process yield and photomasks. Pieces of resist tor