What’s a CDM?
Inside the semiconductor manufacturing facility, chemical distribution modules (CDM) control the supply of ultra-pure process chemicals to the point of use (POU). Since the chemical dispensed at the POU will often come into direct contact with wafers, masks and other critical surfaces, it is crucial the chemical does not contain yield-threatening particle contamination at the point of distribution.
In this study, the Chem 20 chemical particle counter from Particle Measuring Systems (PMS) was connected upstream and downstream of the final 2 nm filter inside a CDM for sulphuric acid. The filter was located at a point just before the acid is dispensed to the POU. The acid was already circulated with 2 nm filtration before being transferred to the day tanks, so the particle measurements upstream and downstream of the filter in the CDM should be fairly similar.
The Particle Contamination Monitoring
Particle counting measurements were performed over several days following the delivery of four different chemical batches. As expected, the particle measurements upstream and downstream of the filter in the CDM were relatively similar for most batches. However, significant difference was identified following the delivery of the first batch. The acid reaching the CDM from the day tanks contained significantly more 20 nm particles than any of the other three batches.
Not only did the Chem 20 chemical particle counter reveal the relatively high level of particle contamination in the chemical reaching the CDM, but the results indicate the additional filtration inside the CDM was successful in reducing the particle contamination to a more typical level before the chemical was dispensed to the critical POU. Only the Chem 20 particle counter has 20 nm sensitivity.
Learn more about the Chem-20 Chemical Particle Counter, and look forward to our next blog on Filter Wetting. Until next time, check out the full analysis of all semiconductor applications discussed in this blog series from Particle Measuring Systems (PMS)!
