New Activities on Particle Counting Measurements


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New Activities on Particle Counting Measurements

The Statistical Methods Task Force of the SEMI Standards North American Liquid Chemicals Committee invites interested parties to join their work on two projects concerning particle counting measurements on liquid chemicals. Briefly, these projects are 1) to develop a method for cross calibrating between two particle analyzers (using one to predict the results of the other) and 2) to develop a method for extrapolating from a measured particle distribution to lower particle sizes (less than the smallest measured channel).

Cross calibration is important because for a given sample commercial particle size analyzers differ, sometimes dramatically, on the measured values of the particle size distribution. Two instruments of the same model, from the same vendor, in the same lab, with the same analysts can produce values that are significantly different. The goal is to develop a guide for using the results from one instrument to accurately predict the results from another instrument. This is important (for example) when two instruments are used on finished goods, when one instrument is replaced by another and the producer and user both measure the product to determine if it is in specification.

The extrapolation problem is driven by advances in particle counting instrumentation. Currently, for most particle size analyzers the smallest channel is 0.1 to 0.2 microns. Counters are available at 0.05 microns and smaller. It is often the case that advances in analytical tools which allow for measurements into regions that were previously terra incognita are a prelude to new specifications that will plant a flag in the newly opened territory. Suppliers would like a way to be able to estimate their capability in the less than 0.1 micron region with their current particle counters.

The Statistical Methods Task Force has a proven record of solving problems common to companies who participate in the semiconductor market. Over the last few years, under the leadership of Tom Bzik (Air Products), the task force has developed a guideline for calculating ship to control limits (SEMI C64-0308) and updated the guide for determining method detection limits (SEMI C10-0305). Even though Tom has stepped down from the helm the Task Force will still strive to remain a value added contributor in the SEMI organization.

If you are interested in being a core member on one or both of these projects, please email task force co-leader Bob Brill at robert.brill@icl-pplp.com. The immediate goal is to set up a time for the first conference call. The target week is January 24.

Core team members will participate in all of the agreed upon conference calls, be willing to work on assignments between calls and report on their findings. The task force plans to hold one conference call per month, or possibly two per month if progress is rapid. These efforts will also require some round robins on commonly shared samples and sharing some data.

The SEMI Standards Liquid Chemicals Committee is chartered to identify and develop international standards fulfilling the technical needs of the industry for liquid chemicals and liquid chemical distribution. Liquid Chemicals Committee standardization includes analytical methods for evaluating chemicals, material specifications for chemicals and the materials used to contain and transport them, performance specifications for liquid chemical distribution systems and components, and guides for definition, use, handling and installation. Current activities of this committee include development of a method for determination of surface areas of polymer pellets, development of chemical specifications for hafnium and zirconium amides, updating of SEMI F63 to meet the ITRS roadmap, and review and updating of the methodology and parameters of existing chemical specifications.

SEMI Standards Watch – January 2011