Recent advances in 193 nm single-layer photoresists based on alternating copolymers of cycloolefins

We report on our recent investigations on the formulation and processing of 193 nm single layer photoresists based on alternating copolymers of cycloolefins with maleic anhydride. Resists formulated with cycloolefin copolymers are compatible with 0.262 N tetramethylammonium developers, have excellent adhesion, sensitivity, etch resistance and thermal flow properties. The effect of polymer structure and composition, dissolution inhibitor structure and loading as well as the effect of the photoacid generator on the resist dissolution properties was investigated. Based on the results high contrast formulations were evaluated on a GCA XLS (NA = 0.53, 4X reduction optics) deep-UV stepper to exhibit 0.27 mu m L/S pair resolution with excellent photosensitivity. Based on the dissolution properties and a spectroscopic examination of the resist, we have designed materials that show < 0.17 mu m L/S pair resolution with 193 nm exposures. In this paper, the formulation methodology will be detailed and the most recent results upon both with 248 and 193 nm irradiation will be described.