Facts
Mechanical stress can impact CMP slurries used in wafer planarization processes. Shear stress in pumps, used in delivery and CMP tools, can cause changes to the particle size distribution due to slurry agglomeration. Particle agglomerates cause wafer defects but also limit the life of filters.

Test conditions
A Levitronix^® BPS-4 pump was evaluated for the effect on the health of Hitachi HS-8005-D4 slurry. A fixed volume of slurry was recirculated at 30 lpm and 2.1 bar. Samples were drawn from the system at selected times for analysis. The particle size distribution of each sample was measured and the concentration of each particle size was compared to the initial concentration.

Results
No significant change was observed in any of the slurry properties measured during the pump test.

Particle concentrations relative to the initial concentration for selected size channels