23 Apr Gas Scrubber, Gas Cabinet, Handling Info for LPCVD process using Arsine (AsH3) gas
[Full Question here]
We will soon be adding an LPCVD tool for a new doping process that we need to bring on line. The process calls for arsine, which we do not have a lot of experience with, but we do know that it is pretty nasty. We’ll need to add a gas cabinet and a scrubber to the Fab to handle this gas. What would you recommend for a scrubber? Is there anything I need to do special to house the arsine bottle? Do I need dual contained tubing due to its toxicity? Thank you for the help.
Answer: Thank you for the question. Yes, arsine is a particularly dangerous gas used in silicon dioxide processing. It is classified as a high toxic, flammable gas so you’ll want to contain it properly. Additionally, since it is a hydride gas it will have an affinity for moisture, so keep your purge gas pure. We would highly recommend a fully automated gas cabinet so you are assured that bottle changes will be both safe and effective at keeping the moisture out of the panel. You will also want a purge gas purifier to knock out any moisture that may be in your purge gas supply. Finally, although it isn’t required by Code, going with coax tubing from the cabinet to the tool would be recommended.
Regarding the scrubber, AsH3 is usually run in small flow rates and can be abated successfully with a resin bed scrubber, so an Edwards M150 GRC would be ideal for this process. The canister that would be used is set up for arsine, and the scrubber is relatively inexpensive.
We have a document (pdf) on our Gas Cabinets page that provides detailed facilitation information on CVD processes that you might find helpful – link is here: Gas Systems for CVD Processes