[labnetwork] Treating silane exhaust from PECVD

[N Shane Patrick]

Hello Hadi,

Being in a similar position at the moment, I can say it’s extremely important to understand your emissions requirements. Environmental regulatory agencies are often empowered to issue significant fines and terminate operations, and simply being an educational institution doesn’t necessarily get you off the hook. YMMV of course by country, state/province, etc. You don’t want to get on the wrong side of inspectors. You likely have resources within your institution that can assist with understanding the legal requirements and, maybe, even help you evaluate what need to do.

As an aside, we can say you likely want to do something about any silane effluent - even with heavy dilution and similar flows, the amount of sand in our exhaust lines says that you want to consider maintenance impacts beyond just legal ones. You will also want to understand the documentation and other expectations any maintenance or facilities teams may have if they need to work on your exhaust systems at any point.

We’re currently looking at dry absorption media canisters, but we’ve honestly raised more questions than answers at the moment, so I can’t really point you in a particular direction with any confidence.

N. Shane Patrick
Manager, Lab Operations and Safety
Electron Beam Lithography
Washington Nanofabrication Facility (WNF) 
National Nanotechnology Coordinated Infrastructure (NNCI)
University of Washington - NanoES
Fluke Hall 129, Box 352143
(206) 221-1045
patricns at uw.edu <mailto:patricns at uw.edu>
http://www.wnf.washington.edu/ <http://www.wnf.washington.edu/>

> On Jan 12, 2023, at 11:35 AM, Hadi Esmaeilsabzali <hadi_esmaeilsabzali at sfu.ca> wrote:
> 
> Dear Colleagues,
> 
> For those who run PECVD at their facilities, I am wondering how you process the exhaust from your systems. 
> 
> We used to treat the PECVD exhaust along with that of the SiNx tube furnace through a TPU. We have recently decommissioned our furnace and TPU as they were too costly to run and are looking at alternative exhaust options for the PECVD only. We use our PECVD tool for oxide and nitride deposition, and it's worth noting that it only uses silane (no ammonia).
> 
> Some colleagues had mentioned that they don't use a TPU/scrubber and send the process waste to the building exhaust (untreated). Given that our PECVD processes use a relatively small silane flow (~30 sccm for up to 30 mins per run each week - all max values) and it is significantly diluted, this sounded a practical option. I am trying to see if others have tried or can comment on this approach, particularly for a silane-based PECVD process. Aside from the flammability concerns, we are also aware of the potential oxide buildup in the exhaust system over time. 
> 
> I appreciate it if you share other (cost-effective) suggestions you might have for us! 
> 
> Thanks,
> Hadi
> 
> Hadi Esmaeilsabzali, PhD
> Nanofabrication Group Manager, 4D LABS
> Simon Fraser University
> 8888 University Dr., Burnaby, B.C. V5A 1S6
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