The Characterization of KrF Photoresists and the Effect of Different Ultraviolet (UV) Absorption Rates on Line Edge Roughness (LER) for Submicron Technology

This research investigates LER characteristics; determine the resist with lowest LER for all process variations and feature size; and investigates the effect of ultraviolet (UV) absorption rates on LER. Three photoresists were evaluated. Characteristics evaluated were depth of focus (DOF), profile, resolution, LER, exposure latitude, iso-dense (I-D) bias and CD linearity. Features tested were from 100nm to 190nm. Results show that resist P0 has the lowest LER with 7.356 3sigma, followed by resist PI and P4 with 3sigma 10.076 and 10.606. In conclusion, low UV absorption rate results in low UV activation, but low photosensitivity and LER. High UV absorption rate results in high exposure latitude, high photosensitivity, but also high LER.