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Hey all,<br>
<br>
This is Mac, at Harvard CNS. Our STS has shown some symptoms of this
due to polymer on the walls coming off in the O2 clean, introducing
fluorine via that route.<br>
<br>
When you wrote "the F peak is clipped of in height during the O2 plasma
clean?" Did you mean it was still there, but shorter? This would
clearly indicate the F is still there, and the only question is where
it's coming from.<br>
<br>
Perhaps a longer chamber clean, with a low-pressure step to spread out
the cleaning plasma, before the stripping runs?...<br>
<br>
Keep in mind that an O2 resist strip can gum up your chamber, and cause
instability in your regular etch processes if you're not careful.<br>
<br>
<br>
Mac<br>
<br>
Mary Tang wrote:
<blockquote cite="mid:4E30A19F.5000506@stanford.edu" type="cite">
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Hi Richard --<br>
<br>
A similar problem was observed and diagnosed on one of our O2 ashers by
one of our industrial labmembers who was a plasma etch engineer at HP.
The cause seems to have been trace amounts Fomblin pump fluid coming
back into the chamber -- Fomblin is basically a polymerized freon, so
there's your fluorine source.<br>
<br>
Mary<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
Paul G. Allen Room 136, Mail Code 4070
Stanford, CA 94305
(650)723-9980
<a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:mtang@stanford.edu">mtang@stanford.edu</a>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://snf.stanford.edu">http://snf.stanford.edu</a></pre>
<br>
<br>
On 7/27/2011 4:58 AM, Morrison, Richard H., Jr. wrote:
<blockquote
cite="mid:94CDEF5D18F0BB4A85B1D78EFBDD6FDA0469538B@exchbk1.draper.com"
type="cite">
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<div>
<p>Hi Everyone, </p>
<p> </p>
<p>Our facility uses an STS RIE tool (100mm wafers), to etch
Nitrides/Oxides/Ti and resist cleans. I have a big problem when we use
O2 to clean off resist from wafers. It seems that just running O2
plasma we etch 1000A/min of SiO2. It should be impossible to etch SiO2
with O2 plasma. </p>
<p> </p>
<p>In trouble shooting we have done the following, change the
Teflon wafer holder, disconnected the SF6, CF4 and CHF3 tanks and
capped the lines, then pumped the machine down and just ran O2 and we
still etched the SiO2 at 1000A/min. We have a plasma scope and the F
peak is clipped of in height during the O2 plasma clean? </p>
<p> </p>
<p>Does anybody have any ideas on what may be going on. </p>
<p> </p>
<p>Thanks in advance, </p>
<p>Rick </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p>Rick Morrison </p>
<p>Senior Member Technical Staff </p>
<p>Acting Group Leader Mems Fabrication </p>
<p>Draper Laboratory </p>
<p>555 Technology Square </p>
<p>Cambridge, MA 02139 </p>
<p> </p>
<p>617-258-3420 </p>
<p> </p>
</div>
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