[labnetwork] Bosch etch foreline and pump powder residue question...

[Aebersold,Julia W.]

Bill we also run 10% O2 with our SF6, too.

Cheers!

Julia Aebersold, Ph.D.
MNTC Cleanroom Manager
Shumaker Research Building, Room 233
2210 South Brook Street
University of Louisville
Louisville, KY  40292

502-852-1572
http://louisville.edu/micronano/

From: Bill Flounders [mailto:bill at eecs.berkeley.edu]
Sent: Wednesday, November 6, 2013 8:36 PM
To: Bob Henderson; Aebersold,Julia W.; 'Ian Harvey'; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Bosch etch foreline and pump powder residue question...

Bob,
I don't expect this to resolve the issue. Some type
of downstream deposit is the price of admission
for any of our etch or deposition tools.
However, I would like to open the following question:

At UC Berkeley (and I presumed most other labs ?)
we use 10% O2 with our SF6 etch step.
This provides oxygen for minimizing sulfur
build up in the foreline - we still get deposits but
they are not as bad as with no O2. I had presumed this
was common strategy. There is some decrease in selectivity
due to resist erosion - but it has been worth it. Greater
concentrations of O2 lead to too much resist loss.

I welcome feedback on this recipe and encourage
addition of some O2 if not using any.

Bill Flounders
UC Berkeley



Bob Henderson wrote:
Has anyone considered using an oxygen/fluorine plasma for removal of the polymer. Since most DRIE systems have an ICP source a fair amount of O/F will be generated that can be used to etch away the carbon rich polymer maybe as far as the gate valve and turbopump. The reactive species probably won't have a lifetime that will extend very far down the foreline but I have seen downstream plasmas that will go a few feet into the foreline before extinguishing. Bob Henderson

From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Aebersold,Julia W.
Sent: Tuesday, November 05, 2013 10:50 AM
To: Ian Harvey; labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Bosch etch foreline and pump powder residue question...

Ian, we noticed the same when we had to replace our turbo pump (very expensive) and were careful with the byproducts from the buildup from the etching process.  It is recommended and we installed a heater on the line from the roughing/backing pump to the turbo, so that the byproducts do not condense and are properly exhausted.   The particles can also buildup on your foreline valve causing it to become stuck or not actuate.

Cheers!

Julia Aebersold, Ph.D.
MNTC Cleanroom Manager
Shumaker Research Building, Room 233
2210 South Brook Street
University of Louisville
Louisville, KY  40292

502-852-1572
http://louisville.edu/micronano/

From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Ian Harvey
Sent: Monday, November 04, 2013 6:36 PM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] Bosch etch foreline and pump powder residue question...

Dear Labnetwork colleagues,

We are installing a used STS DRIE tool acquired from the used tool market and used for Bosch-Si etch.

We are unsettled by the large amount of white powder collected in the foreline and inside the large turbopump.  The turbo is becoming unbalanced as flakes come off, and we are getting ready to trade in the large maglev pump for a refurb, and clean the forelines.

Does anyone have experience with what the powder is (F-C-S-O / EDS analysis attached), its risks, and how to safely manage it during pump removal, packing and declaration for shipping?

Thanks!

Ian

********************************************
Ian R. Harvey, Ph.D.
Associate Director, Utah Nanofab
 &
Micron Microscopy Core
2511 SMBB (USTAR)
University of Utah
801/585-6162 (voicemail)
801/581-5676 (lab main number)
www.nanofab.utah.edu<http://www.nanofab.utah.edu>





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