Photoresist Stripping using Ozone/Deionized Water Chemistry

Abstract

ABSTRACTThe use of sulfuric acid to strip photoresist from silicon wafers is a widely employed technique in the semiconductor manufacturing community. In most cases, the acid is combined with hydrogen peroxide to oxidize stripped photoresist material, though the use of sparged ozone in sulfuric solution is also used to remove resist residues on wafers following the ashing process. Although they have been used for many years, sulfuric acid processes also have proven to be costly. This is due to the need for frequent bath change-outs and the use of high temperature which impose safety and environmental concerns. As a result of these and other considerations, the use of mixtures of ozone and de-ionized water for photoresist stripping has been investigated. Results show that the technique effectively removes hard-baked resist (ashed and un-ashed) from bare silicon and patterned wafers and produces cleaner surfaces (i.e. particles and metals), compared to outcomes from SPM processes.