Patterning nickel for extreme ultraviolet lithography mask application. II. Hybrid reactive ion etch and atomic layer etch processing

Abstract

A two-step plasma-thermal atomic layer etching (ALE) process that is capable of etching Ni with high selectivity with respect to the SiO2 hard mask and high anisotropy is evaluated in this work with a reactive ion etching (RIE) process to highlight the contrast between these two processes and the advantages of combining these two processes to tailor the sidewall profile with greater processing efficiency. The RIE chemistry leveraged the enhanced volatility of chlorinated nickel in the presence of hydrogen atoms. The hybrid RIE and ALE process achieved the desired sidewall profile, with no measurable residual halogen.