[mems-talk] Setting up a small plasma etch system

[Stuart Field]

Hi all: We found an old Technics PEII plasma system and, after some  
tinkering, got it to work. I'm mostly interested in knowing whether  
our current setup is safe, and how to improve it if not.

We're currently running SF6. The mechanical pump has regular  
hydrocarbon oil, and it is vented through a hose to a fume hood. Here  
are my concerns at the moment:

1) When we open the chamber after etching, there is a distinct sharp  
smell. This dissipates after a while. Any ideas of what this is, and  
whether it's really bad for you? I have an idea that it's some  
product of the reaction of fluorine or sulfur with H20, but I'm not  
sure. If we pumped for a long time after reacting but before opening  
the chamber, would this help?

2) After many (~10) runs, a white residue builds up on the aluminum  
plates of the chamber. It can be removed with water. Any ideas of  
what this is?

3) I've heard that sulfurous acid and HF can build up in the pump  
oil, which is both bad for the pump and for those who change the oil.  
I have thought about changing the oil over to an insert oil such as  
Fomblin (which would also allow me to run O2 in the etcher). Will  
this prevent the buildup of these acids?

4) Is simply venting the pump exhaust to a fume hood good enough?

5) Anything else we should know? We're trying to keep this simple, so  
we don't want to spend a lot of money on scrubbers etc. if possible.

Thanks, Stuart

Stuart Field
Associate Professor
Department of Physics
Colorado State University
Fort Collins, CO 80523
970-491-3773 (Office)
970-491-7605 (Lab)
970-491-7947 (Fax)