The removal of hardened photoresist layers by plasma ashing in an important process tool frequently used in the lithographic processing of microelectronic and optoelectronic devices. The existing techniques for plasma resist ashing have undesired ion damage to underlying device layers resulting in degraded device performance. While UV photo ashing avoids radiation damage from plasma ions, these systems are limited by very low throughput. We propose a newly developed dual source of atomic oxygen and VUV photons to ash photoresists at high rates, at low substrate temperatures, and over wide areas with minimum ion damage and residual contamination. A spatially confined active oxygen plasma of disc shape will be used to ash hardened photoresist films with the goal of +5% variation in uniformity over entire 15 cm diameter wafers. Wafers will be located in a field free downstream plasma region, in the near afterglow, where the resist surface is exposed primarily to both a reactive atomic oxygen flux as well as a flux of 130.6 nm oxygen resonance radiation. We aim to measure various polymer ashing activation energies, evaluate radiation damage effects, and measure residual surface contamination for comparison of our ashing approach to traditional methods.
