Effect of Substrate Treatments on Resist Footing in Chemically Amplified System

We investigated the effect of BPSG and SiON substrate treatments (high temperature baking and oxygen plasma treatments using down-flow ashing and reactive ion etching (RIE)) on resist footing in chemically amplified systems. We found that high temperature baking was effective on BPSG, but not effective on SiON. The down-flow oxygen treatment on SiON was effective but RIE oxygen treatment was worse than no treatment on the resist footing. It was suggested that the results of footing using RIE was attributed to contaminants. Since the oxygen plasma treatment is an additional process, we also investigated the resist footing on two types of SiON prepared by different chemical vapor deposition (CVD) process. We found that the resist footing could be improved by selecting appropriate SiON.