Effects of Electron Radiation Generated during E-beam Evaporation on a Photoresist Liftoff Process

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  • Author: Kezia Cheng, Minh Le, Donald Mitchell, and Larry Hanes
Many new resists have been developed in recent years designed for liftoff metallization process. Chemically amplified resist (CAR) achieves the re-entrant  profile due to the nature of the exposure and acid diffusion kinetics. Other approaches like post exposure bake image reversal process can attain similar results. Most of these resists share a common characteristic - given enough thermal or radiation energy, the polymer will cross link rendering it resistant to strip chemicals. In the case of the bi-layer resist process, electrons can cause resist blistering in the PMMA layer [1]. There have been other reports of unintentional exposure of PMMA and PMGI during the E-beam deposition process in the compound semiconductor community.