Focus Spot Reduction by Brush Scrubber Cleaning

Abstract

of preventive backside cleaning steps. These cleaning steps can be introduced after processes that generated high backside defect counts or right before a lithographic wafer exposure. In this study that was performed at imec’s 300mm cleanroom facility, the study objective was to evaluate the focus spot reduction performance of a stand-alone scrubber in a case study featuring known focus spot generating equipment sets. . In the first part of the study, monitoring of various production tools in terms of backside cross-contamination was done. A set of equipment’s that generated high backside defect counts was selected for generating adequate backside contaminated test material for the cleaning evaluation. This backside contaminated test material was used in our cleaning experiments and evaluation of focus spot reduction by performing leveling tests on an immersion scanner that was able to measure out of plane deviations.