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MAXIMILIAN A. BIBERGER & PAUL SCHILLING, Supercritical Systems Inc., Fremont, CA, USA
DON FRYE & MICHAEL E. MILLS, The Dow Chemical Company, Midland, MI, USA

ABSTRACT

Anovel cleaning technology for removing photoresist and photoresist residue from semiconductor wafers is introduced. This cleaning technology is a non-plasma, environmentally friendly technology using supercritical CO2 (SCCO2) and co-solvents to clean the substrates. The wafers are being cleaned in a single wafer, 300 mm compatible chamber under moderate pressures, between 8.6 MPa and 19 MPa, and moderate temperatures, between 40ºC and 70ºC. Cleaning with SCCO2 and co-solvents is a “dry in – dry out” process technology, consisting of a cleaning and a rinsing / drying step performed in the same chamber with a total processing time between two and four minutes, depending on the application. The above mentioned processing times include pressurisation and de-pressurisation of the chamber. It was demonstrated that the co-solvent usage is in the range of 10 ml to 40 ml per wafer run and that the amount of co-solvents, as well as the time for cleaning and rinsing / drying, is independent of the sample size (wafer chips versus a whole 200 mm wafer). Cleaning with SCCO2 and co-solvents was successfully applied to a broad range of applications from front end applications (ion implant) to dual damascene Cu technology with standard oxides and low-k materials. Based on the results to date, cleaning with SCCO2 and co-solvents has the potential to combine ashing and wet cleaning into one process step, overcoming the potential shortcomings of ashing and wet cleaning with respect to high aspect ratio features, dual damascene and low-k technology, and reducing the amount of solvents and water dramatically, resulting in an enabling, very cost effective cleaning technology.