CMP Slurry Filtration

Process & filtration objectives

CMP slurry is a formulation containing useful abrasive particles, not simply a dirty liquid. Filtration targets oversized particles and agglomerates. A clearer filtrate can indicate unwanted loss of the abrasives that perform the polishing.

Storage, blending, recirculation and delivery change slurry condition. Comparing particle distributions, solids and differential pressure at defined locations helps separate incoming variation from pipe deposits and filter selection effects.

Typical process pathway

01
Receipt and storage
Record batch, solids, storage time and particle distribution to establish the incoming slurry baseline.
02
Blending and transfer
Track changes after dilution, mixing and pumping so formulation changes are not mistaken for filter failure.
03
Recirculation
Manage coarse particle loading while checking whether repeated passes alter useful particle distributions or concentration.
04
Point of use
Control particles introduced during delivery near the tool, with attention to venting and startup stability.

This is a typical task pathway. Confirm sequence, equipment and operating conditions for the project.

Filtration points & selection rationale

Process point	Filtration task	Selection rationale
Tank outlet	Manage coarse contamination and agglomerates	Compare dirt capacity with passage of useful abrasives.
Recirculation loop	Control oversized particles over time	Consider flow, shear and number of passes together.
Tool inlet	Limit oversized particles reaching the process	Balance footprint, retained volume and stabilization after replacement.

Verification & operating records

Evaluation item	Recording & comparison
Particle distribution	Use consistent sampling and dilution; an average diameter alone can hide the oversized tail.
Useful components	Record solids and critical formulation properties alongside particle counts to assess formulation retention.
Operating behavior	Plot differential pressure against processed volume and relate each batch to scratch or defect observations.