High-purity CO₂ snow cleaning for sensitive semiconductor processes

1. The Challenge

In semiconductor manufacturing, optical components such as deflection mirrors must be cleaned to be absolutely free of residues. Even the slightest contamination in the range of ppt (parts per trillion) can jeopardize wafer quality and thus yield. Cleaning with CO₂ snow requires ultra-pure CO₂, which must not be contaminated even during compression. Conventional compression techniques carry the risk of contamination from lubricants or sealing systems. Therefore, a solution was sought that could compress CO₂ extremely cleanly and reliably.

2. The sera Solution

The customer uses a metal diaphragm compressor from sera to compress high-purity, gaseous CO₂. The compressed CO₂ is then cooled, liquefied, and expanded through a nozzle, creating the finest CO₂ crystals (“CO₂ snow”). This snow is used to clean the sensitive mirrors in production completely free of residue. The compressor technology used operates lubricant-free and hermetically sealed, reliably preventing contamination of the medium. This ensures that the required purity of the process is maintained even during the production of the cleaning medium.

3. Customer Benefits

• Reliable production of high-purity CO₂ snow for sensitive cleaning processes
• No contamination of the CO₂ during compression
• Stable, reproducible cleaning quality in wafer manufacturing
• Many years of trouble-free operation of the system

4. Brief Summary

The project demonstrates that extremely high purity requirements in semiconductor manufacturing can only be reliably met with consistently clean and hermetically sealed compressor technology.