Pattern collapse in the top surface imaging process after dry development

Abstract

In this article the pattern collapse in a 193 nm top surface imaging process after dry development is described. We dry developed the resist with O2 and SO2 plasmas at low temperature in order to replicate a fine pattern profile. Pattern collapse occurred because of stress from neighboring patterns when SO2 was added at low substrate temperatures and the line/space binary pattern was below 0.15 μm. We found, using Auger electron spectroscopy analysis, that a sulfuric compound covered the side walls of the pattern when SO2 was used. We propose a pattern collapsing mechanism caused by the reaction of H2O with the evaporation of water adsorbed by the sulfuric compound on the resist pattern. It is therefore effective to decrease the sulfuric compound on the patterns before the wafer is removed from the etching chamber. Finally, we successfully replicated a sub-0.10 μm line and space pattern without pattern collapse.