EUV resist performance enhancement by UV flood exposure for high NA EUV lithography

Abstract

The enhancement in chemical gradients between the EUV exposed and unexposed areas can generate a wider process window, possibly, a smaller stochastic defectivity, and a lower local CD uniformity in EUV resists. This enhancement, in turn, helps to overcome the challenge of the small process window in high NA EUV lithography. In this work, a new concept resist, which is developed based on our chemical gradient enhancement technique model, is used to drive the chemical gradient upward chemically. The resist also has the capability of absorbing UV selectively at EUV exposed areas. Therefore, the UV flood exposure system, which has been discussed in Photosensitized Chemically Amplified Resist (TM) (PSCAR (TM)), is used as another key part to further enhance the new resist. The new concept resist with UV lights was confirmed to give 15.1 % improvement in its EUV sensitivity and, simultaneously, 25.0 % improvement in local CD uniformity. This technique might be one of the solutions to bring CAR resist further into high-NA EUV lithography.