Carbon Hard Mask Opening Process Development with Novel Sidewall Passivation in Memory Manufacturing

When the logic memory cells are scaled, the aspect ratio of the holes increases, and the profile control of these structures becomes increasingly challenging. The carbon hard mask serves as a sacrificial template to transfer its profile to the underneath layer. It is expected that the etched features have vertical profile to achieve better CD uniformity and less pattern roughness. In this article, we report a study on the commonly carbon hard mask etching process with O2 and SO2 plasma. In order to achieve bowing free carbon profile, a novel sidewall passivation gas is added for the profile control during hole manufacturing in logic memory application.