From EntegrisReviewed by Danielle Ellis, B.Sc.Apr 29 2026
In this interview, AZoMaterials speaks with Mark Bumiller, Technology Manager for the AMH Instrumentation Division at Entegris, about particle size and count monitoring of CMP slurries and its role in semiconductor process control.
This interview summarizes the recent webinar presented by Mark - you can watch the webinar here.
Can you please introduce yourself and your role at Entegris?
My name is Mark Bumiller, and I am the Technology Manager for the AMH Instrumentation Division at Entegris. I have worked in particle size analysis for around 40 years and have conducted tens of thousands of particle characterization measurements, many of them focused specifically on CMP slurries.
At Entegris, I work within the Advanced Purity Solutions group, where we develop and supply instrumentation used to measure both mean particle size and large particle counts in CMP slurries. These tools help semiconductor manufacturers monitor slurry performance and maintain the quality required for advanced wafer processing.
Why is particle size monitoring so important for CMP slurries?
Particle size is one of the most critical parameters influencing the performance of CMP slurries. The abrasive particles in these slurries are typically sub-micron materials, often silica or ceria, and their size directly affects polishing performance and removal rates during wafer processing.
Even small differences in particle size distribution can significantly impact how effectively the slurry polishes the silicon wafer surface. Because of this, semiconductor manufacturers must carefully monitor particle size to ensure consistent performance and avoid variability during the polishing process.
What techniques are commonly used to measure the mean particle size of CMP slurries?
Several techniques are used to measure mean particle size in CMP slurries, but the most common are dynamic light scattering (DLS) and laser diffraction.
Dynamic light scattering measures fluctuations in scattered light caused by the Brownian motion of particles in suspension. By analyzing these fluctuations, the system calculates particle size and distribution.
Laser diffraction measures the pattern of light scattering at different angles as particles pass through a laser beam. This technique provides fast and repeatable results across a broad size range.
Why is it necessary to measure large particle counts in addition to mean particle size?
While mean particle size provides valuable information about the abrasive particles in a slurry, it does not fully describe the tail of the particle size distribution.
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Even when the average particle size is small, a small number of larger particles may still exist. These large particles can damage wafers during polishing by creating scratches or defects on the wafer surface.
Because of this, monitoring large particle counts is essential for maintaining wafer quality and semiconductor manufacturing yield.
What technology is used to measure large particle counts in CMP slurries?
Large particle counts are typically measured using single particle optical sizing (SPOS) technology, implemented in instruments such as the AccuSizer.
In this approach, particles pass through a laser beam one at a time inside a sensor. As each particle moves through the beam, it blocks or scatters light, generating a signal that is converted into particle size and concentration information.
This method enables precise measurement of the number of particles above a specific size threshold, such as 0.5 microns.
How do large particles affect semiconductor manufacturing yield?
Large particles can significantly impact wafer quality. There is often a strong correlation between the number of large particles in a slurry and the number of defects or scratches that appear on the wafer.
Since semiconductor wafers can be extremely valuable, even a small increase in defect rates can have a major financial impact. Monitoring large particle counts, therefore, plays an important role in process control and yield optimization.
How are these measurements performed in the laboratory?
In laboratory testing, CMP slurry samples are typically diluted and then analyzed using instruments designed to measure particle counts accurately.
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These systems automatically dilute the sample to an optimal concentration and then pass the diluted slurry through a sensor to measure particle size and concentration. Laboratory testing is used throughout the CMP supply chain to verify slurry quality before use.
What advantages does online monitoring offer for CMP slurry analysis?
Online monitoring provides continuous visibility into slurry behavior within the manufacturing process.
Rather than taking periodic samples to the laboratory, online systems monitor particle counts and particle size directly within the slurry delivery system. This allows manufacturers to identify process changes immediately and respond before wafer defects occur.
How can online monitoring improve CMP process control?
Online monitoring allows engineers to track trends in particle counts over time as slurry moves through the delivery system.
This helps identify issues such as aggregation, filtration problems, or changes in slurry quality. It also allows operators to determine when slurry should be replaced or when filters require maintenance.
What role does particle monitoring play in optimizing CMP systems?
Particle monitoring helps engineers evaluate filters, pumps, tubing, and other components within slurry delivery systems. By observing how particle counts change under different conditions, manufacturers can optimize equipment and operating parameters.
Ultimately, these measurements help deliver cleaner slurry to polishing tools, improving wafer quality, process stability, and overall manufacturing yield.
About Mark Bumiller
Mark Bumiller is the Technology Manager for the AMH Instrumentation Division at Entegris and has over 40 years of experience in particle size analysis. He has conducted tens of thousands of particle measurements throughout his career and has published numerous papers on particle characterization. Bumiller h
as also delivered hundreds of technical webinars and has served on multiple industry committees focused on particle sizing standards and technology development.
This information has been sourced, reviewed and adapted from materials provided by Entegris.
For more information on this source, please visit Entegris.
Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of AZoM.com Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.