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Protect wafer yield from large particles in CMP slurry
Particle defects don’t announce themselves. They show up as micro-scratches, dishing, and yield loss after the wafer has already moved through polish. Gel particles, agglomerates, and oversized abrasives suspended in chemical mechanical planarization (CMP) slurries may be the source. They form during blending, settling, pH shifts, and interaction with valves and pumps. Once they reach the polish head, the damage is done.
For those managing defectivity excursions or tracking the cost of ownership through a node transition, the connection between slurry particle control and device yield is direct. Thermo Fisher Scientific particle control filtration solutions are designed to address that connection from slurry manufacturing through point-of-use at the CMP tool.
How CMP slurry filtration works
There are two sides to one slurry. On the manufacturing side, filtration runs at four points: DI water, raw materials, post-blending, and final filtration before drum or tote fill. On the fab side, slurry moves from the blending/mixing station into a day tank, through a distribution loop running at 5–15 gpm, and to each CMP tool at 100–500 mL/min. The logic is “classify or clarify.”
- Graded-porosity filters at post-blending and the distribution loop remove agglomerates and gels without sacrificing flow or stripping desired particles.
- Sharper cut-off membrane filtration classifies at the final fill and at the point of use, removing the oversized particles on the right-hand tail of the Particle Size Distribution (PSD) while preserving solids content.
Compare options to conventional CMP slurry filtration
Conventional melt-blown and single-layer non-woven media were not engineered for CMP environments. As the mean particle size in advanced slurries trends below 100 nm, those media become less effective. High pressure drops, inherent hydrophobicity, and inconsistent pore geometry under dynamic conditions can limit their performance.
Graded-porosity multi-zone and pleated membrane filtration may be solutions. The rigid, all-polypropylene structure of Betapure Filters maintains consistent particle retention even under increasing differential pressure, with low fines shedding and low extractables. Broad chemical compatibility covers acidic, neutral, and alkaline slurry chemistries. Extended service life can reduce filter change-outs, and the slurry waste and process interruptions that go with them.
Chemical mechanical planarization solutions by application
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Protect every wafer that reaches the polish head. On the fab side, slurry travels from the mixing station through the day tank, into the distribution loop, and finally to each CMP tool. Gels and agglomerates build up in the day tank as fluid levels drop. Oversized particles generated in the distribution loop must be removed before they reach the tool.
Betapure PPK Filters and Betapure AU/AL Filters enable graded-porosity filtration that clarifies recirculating slurry in the distribution loop. At the point of use, LifeASSURE EMC Filters and LifeASSURE EPF Filters offer membrane filtration with the sharp classification cut-off needed immediately before the polish head, removing oversized particles without altering percent solids.
This combination helps you protect high-value wafers and tools, support consistent defectivity performance, and reduce unscheduled tool downtime caused by slurry excursions.
This combination helps you protect high-value wafers and tools, support consistent defectivity performance, and reduce unscheduled tool downtime caused by slurry excursions.
LifeASSURE EMC Filters are designed for DI water and UHP (ultra-high purity) chemical polishing. The pleated nylon membrane construction is hydrophilic, requiring no IPA pre-wetting. The combination of FlexN multi-zone media and Advanced Pleat Technology (APT) supports high flow at low differential pressure.
Keeping utility streams particle-controlled directly affects slurry stability, post-CMP clean efficacy, and overall fab particle budgets.
Sub-100 nm slurries demand a different approach to filter selection. As the mean particle size falls below 100 nm, conventional melt-blown media struggle with both fine-particle classification and pressure-drop performance. Membrane filtration offers a higher-precision alternative, but surface charge matters as much as pore size.
Research presented at ICPT 2025 tested three 0.45 µm membranes, positively charged nylon, neutral PES, and negatively charged PES, against a 50 nm ceria slurry at pH 4.8 with zeta potential -48.7 mV. The neutral-surface-charge membrane (PES 0) achieved longer filter life and lower adsorption of unwanted fines. Charged membranes caused electrostatic interaction with the slurry particles, plugging pores and reducing filter life.
Matching membrane surface charge to slurry zeta potential is the engineering foundation for next-node slurry classification with stable flow.
Explore products for chemical mechanical planarization
Betapure AU/AUL Filters and Betapure PPK Filters classify CMP slurry across the manufacturing and distribution workflow. Additional Betapure Filters are available for specific slurry chemistries and classification applications.
Product links on this page currently direct to Solventum.com. Product information will soon be available on Thermofisher.com as part of our ongoing integration.
Frequently asked questions
CMP defects, such as micro-scratches, chatter marks, dishing, and erosion, often trace back to oversized abrasive particles, gel agglomerates, and external contamination entering the slurry. These large particle counts restrict intended electrical and metal layers during chemical mechanical polishing. Source control through slurry blending, settling in the day tank, shear from pumps and valves, and insufficient filtration at many stages of the slurry workflow.
Filtration directly influences the removal rate by controlling the particle-size distribution and concentration entering the polish head. Over-aggressive filtration or charged-membrane adsorption can strip desired abrasive particles, shifting slurry chemistry and depressing removal rate. Undersized filtration leaves agglomerates in place, causing yield-killing defects. Neutral-surface-charge membrane filtration is a strategy for maintaining stability of the removal rate while targeting the oversized-particle tail.
Graded porosity filtration clarifies broad cut-off contamination at the post-blending and distribution stages, handling high solids loads while extending filter service life. Pleated membrane filtration offers sharp, absolute cut-off classification at final filtration and point-of-use, removing the oversized PSD tail without stripping percent solids. System-level CMP filtration design typically uses both in sequence: graded-porosity first for classification and membrane filtration second for precise classification.
Related resources
Intended use of the products mentioned on this page vary. For specific intended use statements, please refer to the Instructions for Use for the product.