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

[Bob Henderson]

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]
On Behalf Of Aebersold,Julia W.
Sent: Tuesday, November 05, 2013 10:50 AM
To: Ian Harvey; 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]
On Behalf Of Ian Harvey
Sent: Monday, November 04, 2013 6:36 PM
To: 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

 

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