Fluoropolymer-based resists for a single-resist process of 157 nm lithography

We investigated two types of main-chain fluorinated polymers and found that incorporating fluorine into their backbones reduced their absorption coefficients to less than 1 mum(-1) at 157 nm and showed good dry-etching resistance. Fluoropolymer dissolution during development was studied using a quartz-crystal microbalance and evaluated from the standpoint of molecular structures and polymer acidity. The fluorine and hydrophobic effects, rather than the polymer acidity effect, were found to play the dominant role in forming the swelling layer during development. The use of main-chain fluorinated polymers for the base resin of positive-tone resists results in fine imaging with a film thickness of 300 nm. The incorporation of fluorine into the backbones will thus enable these polymers to be used as single-layer resists for 157 nm lithography. (C) 2002 American Vacuum Society.