Control of acidity of the substrate for precise pattern fabrication using a chemically amplified resist

摘要

Abstract: The chemically amplified (CA) resist has been widely and generally used for sub-quarter micron device fabrication using a KrF excimer laser stepper. However many problems have been revealed and laborious efforts have been seriously undertaken to solve them. Among these issues, we have been examining the dependence of the resist characteristics on the substrate properties. In order to control and minimize the fluctuation of the critical dimension, we have been evaluating the relation between the cleanliness of the substrate materials and the CA resist patterning characteristics, especially, we have been focusing on the effect of a wet cleaning process-step which is a necessary and important process-step for actual device manufacturing. Among the several materials which we evaluated, we found that the characteristics of an amorphous carbon(a-C) film used as an anti-reflective coating were significantly affected and changed by the sulfuric acid and hydroperoxide mixture (SPM) cleaning. For the other materials, no characteristic changes in the cause of this SPM cleaning were observed, and this cleaning method was effective and applicable to almost materials except the a-C film. In case of the a-C film, the acidic residue remained after the cleaning, and this contamination changed the acidity of the film. The resist patterning characteristics fabricated on the contaminated film were drastically changed, and pattern collapse occurred. In order to diminish this remaining contamination and control the acidity of the contaminated substrate, we tried to apply a high temperature treatment, an alkaline treatment and a UV cure treatment.!15