The kinetics of a negative-tone acrylic photoresist for 193-nm lithography

Abstract

Polymethacrylates with tert-alcohol ester were synthesized as negative-tone chemical amplification photoresists (CAMPs) for 193-nm microlithography. The acid-catalyzed dehydration reaction of the CAMPs was analyzed via Fourier transform infrared. The crosslinking behavior following the dehydration reaction of the exposed CAMPs made it possible for them to be used as negative-tone photoresists. During the postexposure-baking process of the resists, the decay of the active proton concentration due to the evaporation and trapping of the active acid was lumped to a time constant (τ). Kinetic studies revealed this dehydration reaction was the first order to the hydroxy group and proton concentration. The introduction of the isobornyl methacrylate monomer into the resists produced a higher glass-transition temperature as well as a higher reactive ion etching resistance. The lithographic performance was investigated by use of isopropyl alcohol as a developer under various processing conditions. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 954–961, 2000