Resist processes for hybrid (electron-beam/deep ultraviolet) lithography

This article describes the different mix and match writing strategies using both an optical deep ultraviolet (DUV) stepper (ASML/90) and an electron-beam (e-beam) system (LEICA VB6HR) with both positive and negative tone chemically amplified resists. These resists, mainly developed for DUV applications, have shown very good performance under e-beam exposure. Negative tone resists such as the Shipley XP90166 and UVN2, and positive tone resists such as the Shipley UVIII and UV5 have been optimized in terms of soft bake temperatures, postexposure bake temperatures, and development process. Resolutions in the range of 40–50 nm have been obtained using a 50 keV accelerating voltage. Delay time effect has been quantified and different behaviors under vacuum and in air have been pointed out.