Effects of N2, O2, and Ar plasma treatments on the removal of crystallized HfO2 film

Abstract

The effects of plasma treatment using Ar, N2, and O2 on the removal of crystallized HfO2 films in a dilute HF solution were studied. The resulting damage in source and drain regions, and recess in isolation regions were also investigated. It was found that plasma nitridation with an ion energy of several hundred electron volts can lower the wet etch resistance of crystallized HfO2 films up to 70 Å thick through the generation of Hf-N bonds. However, thermal nitridation did not introduce sufficient nitrogen into bulk crystallized HfO2 films to lower wet etch resistance. Plasma nitridation without bias power introduced nitrogen to the crystallized HfO2 in the region only within 10 Å of the surface. The enhancement of the etch rate of crystallized HfO2 in dilute HF and the amount of recess in the active and isolation regions using N2, O2, and Ar plasma treatment have been evaluated. Results show that N2 plasma treatment is the most effective in enhancing the removal rate of crystallized HfO2 in dilute HF and minimizing recess on substrate among the plasmas studied.