Slurry Flow Rate Pressure vs. Particle Size Distribution In a Bellows Pump Circulation System

摘要

In order to ensure the quality of slurry, some parameters, including pH value, density, solid content and particle size distribution (PSD) of slurry are often monitored in the semiconductor CMP process. PSD is the most direct quantity, which greatly affects the slurry polishing rate and the quality of polishing. In a slurry delivery system, PSD shifts with the pumping speed and flow rate, so for a tighter process control, the in-situ PSD value at POU is an important index to monitor the scratch level of the slurry. A bellows pump is often used in a conventional slurry delivery system; therefore, we studied the relation of PSD vs. pumping speed and flow rate within a bellows pump circulation system using a in-line slurry monitoring instrument, SlurryChek, by PMS. The pumping speed and the pressure difference in delivery system were also investigated. Generally, the concentration of large particles (> 1μm) increases with the pump speed, which may result from the increase in the shear force of the pump at high flow rate. A commerical damper was connected to reduced the pressure turbulence and pressure pulse variation in the slurry delivery system. Our results showed that the variation of PSD and the increase of large size particles greatly reduced after the installtion of damper.