[labnetwork] foreline and exhaust line maintenance
Bob Hamilton
bob at eecs.berkeley.edu
Wed Sep 15 12:19:42 EDT 2010
Iulian,
The UC Berkeley Microlab's biggest concern has been soaking
the silicon nitride forelines in water, overnight. If left
open to air they will corrode. In water this does not happen
to the same degree. The ammonium chloride resides swell and
become easy to remove after a 12-24 hour soak. There is
likely some trapped DCS in these films which water helps
mitigate. One can see some bubbles emanating from the
coating when first immersed so this should be done in an
exhausted enclosure. In the past, we have made long troughs
by buying PVC piping, putting on end-caps on and slicing it
in half, longitudinally on a band saw; however, our current
forelines do not exceed a few feet in length.
Poly generates red powder which we assume is silicon and
phosphorus compounds. Scratching this material generates
some sparks, even after long exposure to air; however, I
have not seen it be a particular problem. It wipes off
easily with towels. One gets a whiff of Eau D'phosphine
doing this work. We can set off our hand-held hydride
detector, above its 1 ppm threshold when sampling forelines
so you may want a respirator for the short time it takes to
move these parts. A rubber glove over each end serves well.
I would not dispose of any LTO residues in a trash container
unless it is fire-proof. I prefer to wet the towels to
assure they are reacted and not flammable.
The LTO exhaust deposition seems to have no particulary
issues except some residual PH3 odor.
UC Berkeley does not use TEOS in lpcvd so I do not have
experience with this material.
Bob Hamilton
On 9/15/2010 5:52 AM, Iulian Codreanu wrote:
> Good Morning.
>
> I understand that the foreline and pump exhaust line on
> tools using particular precursors (e.g. silane) need to be
> made of short (4-5 ft) sections so that they can be immersed
> in a liquid bath to neutralize the exhaust byproducts that
> accumulate over time.
>
> If you do something similar in your fab could you please
> share your experience with us?
>
> Thank you very much.
>
> Iulian
--
Robert Hamilton
UC Berkeley Marvell Nanolab
Equipment Manager
Rm 520 Sutardja Dia Hall
Berkeley, CA 94720-1764
bob at eecs.berkeley.edu (preferred)
510-642-2716
510-642-2916 (Fax)
510-325-7557 (Personal Cell)
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