MAKING SUPERCRITICAL CO{sub}2 CLEANING WORK: PROPER SELECTION OF CO-SOLVENTS AND OTHER ISSUES

摘要

Supercritical CO{sub}2 (scCO{sub}2) cleaning is an exciting green technology to remove heavy organics (resist and/or residue) with complete rinsing and drying of the wafer in one single step. However, there are a number of concerns about implementing scCO{sub}2 cleaning in the industry. In this paper, those concerns are listed and some of them are addressed in detail. One of the challenges is selection of the proper co-solvent for scCO{sub}2 processing. This paper will focus on the differences from ambient pressure cleaning, guidelines for choosing the correct co-solvent(s) for scCO{sub}2 cleaning, the safety aspects of the scCO{sub}2 tool and material compatibility issues. Consequences of selection of a suitable co-solvent mixture resulting in decreased process time, decreased chemical consumption and lower operating pressures are presented. The pros and the cons of both industry approaches to scCO{sub}2 cleaning (using a mixture of co-solvents and/or using scCO{sub}2 philic surfactants) are also discussed in detail.