Airborne Contamination of a Chemically Amplified Resist. 2. Effect of Polymer Film Properties on Contamination Rate

Many chemically amplified resists exhibit severe degradation of lithographic properties upon exposureto very low concentrations of organic base vapor. Measured rates of absorption of such contaminants by thin resist and polymer films vary over a wide range depending on the chemical structure of the polymer comprising the film. We describe here a study aimed at identifying those film characteristics that significantly influence contaminant uptake rates. We test whether the kinetics of contaminant absorption are controlled by (1) the amount of residual casting solvent in the film and/or (2) the physical properties of the polymer comprising the film. Radiotracer techniques are used to quantify casting solvent residue in thin polymer films and to characterize the kinetics of absorption by such films of N-methylpyrrolidone, a common airborne contaminant. The results of this study provide guidance in the design of chemically amplified resists resistant to airborne chemical contamination. © 1994, American Chemical Society. All rights reserved.