Effect of Shear Stress and the Influence of Different Pump Methods on CMP Slurry
Mark Litchy, CT Associates, Inc.
Reto Schoeb, Levitronix GmbH
Conventional wisdom suggests shear stresses generated by centrifugal pumps are too high to allow use of the pumps for delivery of shear sensitive slurries. This paper shows that a shear-optimized centrifugal pump is capable of circulating slurry with minimal damage compared to traditional slurry delivery methods. Formation of large particles, which can cause wafer defects and limit the life of system filters, was significantly less with a centrifugal pump compared to other delivery methods.
Semiconductor International, 27 (12), 87-90 (2004)