Photoresist Damage in Reactive Ion Etching Processes

Abstract

Photoresist damage and patterned feature distortions generated in reactive ion etch (RIE) processing of , thin films were studied as a function of the applied radio frequency power density in two RIE reactors. The photoresist damage was found to originate from plasma‐ and thermal‐induced phenomena that characterize the etching plasma. The onset of photoresist damage was correlated to the glass transition temperature ( of the thermal‐cured photoresist. was found to be 116 ± 8°C for the AZ P4330 positive photoresist and correlated with an onset radio frequency power density of 2.7 ± 0.2 W/cm2. Below , the plasma‐induced phenomena manifested as photoresist etching, hazing, and creep. Above the of the photoresist, thermal‐induced phenomena, manifested as severe photoresist degradation and creep, was found to be the dominant mechanism for the photoresist damage. A model is also presented that predicts and explains the photoresist behavior in an RIE environment with respect to the of the photoresist and as a function of the applied radio frequency power density.