CMP Filter Test in CMP slurries
In an effort to reduce the number of oversized particles in CMP slurries, filter testing has been performed.
The image shows the Accusizer FX results for a CMP slurry before and after it has been passed through a 1 micron filter. The Accusizer FX uses focused extinction wherein the view volume through which particles pass through the sensor is drastically reduced. This reduction provides much higher sensitivity and particle coincidence limit. Therefore the minimum particle size limit is lowered and the coincidence limit is increased. This system is ideal for an online application where predilution is not feasible.
After filtration there is a dramatic decrease in the concentration of oversized particles in the “tail” of the distribution. The inset shows the same slurry with 10x magnification. Here the reduction in the number or aggregates >2 microns is becomes quite apparent. The ability to size and count aggregates in CMP slurries gives the user invaluable knowledge that can save time and money. With the Accusizer FX, conventional SPOS technology is taken to a higher level and provides the sensitivity and reliability needed for online processes.