Effect of H2/He plasma treatment on porous low dielectric constant materials.

Porous low- k films, deposited using a plasma-enhanced chemical vapor deposition (PECVD) porogen-based process, were treated by H 2 /He plasma at varied temperatures ranging from 25 °C to 350 °C in this study. Two different plasma treatment reactors: capacitive coupling plasma (CCP) and remote plasma (RP) systems, were used to compare the impacts of H 2 /He plasma treatment on the porous low- k film. Experimental results indicate that H 2 /He plasma treatment in CCP system caused a larger degradation in low- k film's properties due to the physical-chemical reaction by H ions, radicals, and VUV photons as compared to that in RP system with only presence of H radicals. Additionally, the operation temperature of H 2 /He plasma treatment operated in the CCP and RP systems resulted in an adverse effect. H 2 /He plasma-treated low- k films operated in CCP system at elevated temperatures exhibited a large scission of Si–CH 3 groups, a large increase in k -value and leakage current, and a large degradation in breakdown field and TTF. However, the damage induced by H 2 /He plasma in RP system was alleviated by increasing the operation temperature. Additionally, as the operation temperature is raised to 350 °C, the positive effects with the reduction of k -value and the improvement of reliability were detected in H 2 /He plasma-treated low- k films. These enhanced properties are attributed to the removal of carbon-based porogen residues by He/H 2 plasma in RP system at high temperatures. Consequently, remote He/H 2 plasma treatment operated at high temperatures is a damage-free process for porous low- k films as it is used to strip resist during the fabrication of interconnects. [ABSTRACT FROM AUTHOR]