Evaluation of manufacturing handling characteristics of hydrogen peroxide-based tungsten CMP slurry

In a typical production-scale fab, CMP slurry will circulate through a bulk delivery system and fab piping approximately 100 times before being consumed. During these “turnovers”, the slurry will encounter abuse from many sources, including decomposition of constituents. Change in any physical or chemical property during its lifetime, particularly hydrogen peroxide (H₂O₂) concentration, may affect polishing performance. In this paper, a commercially available CMP slurry used for tungsten polishing was subjected to an accelerated aging and handling evaluation to determine its handling characteristics in a bulk slurry distribution system used in semiconductor manufacturing. In this accelerated aging test, Cabot SemiSperse^R W-2000 was subjected to 3000 storage tank turnovers during a seven-day test period while monitoring slurry health parameters, including pH, density, weight percent solids, and particle size distribution. During this period, the slurry showed minimal changes in all normal slurry health parameters. The H₂O₂ oxidizer did decompose as expected, but was readily replenished by following the manufacturer´s recommendations of periodic assay analysis and dosing with replenishing H₂O₂. Cabot Semi-Sperse^R W-2000 tungsten polishing slurry with H₂ O₂ oxidizer should be compatible with bulk slurry delivery systems, especially those using vacuum-pressure dispense engines