Utilization of critical fluids in processing semiconductors and their related materials

The use of carbon dioxide in its various states: supercritical (SC-CO2), liquid (L-CO2) or pellet form (snow-CO2) for processing and cleaning in semiconductor fabrication and related electronic devices is assessed in this review. An understanding of the fundamental mechanisms responsible for carbon dioxide-based processing, as in surface cleaning, is lacking. Although carbon dioxide is an excellent solvent for removing non-polar contaminants from a variety of surfaces, other CO2-based cleaning and surface modification processes are based on mechanical or morphological-induced changes in the interfacial region. The extremely low surface tension of CO2 is a favorable property in terms of its rapid and complete removal from the substrate after a treatment has been affected, and this characteristic of CO2 also accounts for its negligible effect on the morphology of the substrate, as utilized in the microelectronic industry. Applications of critical fluids in integrated circuit manufacturing operations, such as wafer cleaning, film deposition, photoresist stripping, drying, and particulate removal are noted.