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<p>Thanks Tony!</p>
Yes, I was trying to remember what Ted Berg, our furnace guy at the
time, did about the "champagne nitride". I don't recall the
plumbing solution exactly, but he took a cue from Berkeley and found
a way to ensure a constant, low draw during unload.<br>
<p>Mary<br>
</p>
<pre class="moz-signature" cols="72">--
Mary X. Tang, Ph.D.
Managing Director
Stanford Nanofabrication Facility
Paul G. Allen Building
420 Via Palou Mall
Stanford, CA 94305
<a class="moz-txt-link-freetext" href="https://snf.stanford.edu">https://snf.stanford.edu</a>
<a class="moz-txt-link-abbreviated" href="mailto:mtang@stanford.edu">mtang@stanford.edu</a></pre>
<p><br>
</p>
<div class="moz-cite-prefix">On 8/3/2021 2:29 PM, Tony Whipple
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAOzkqn+oaKrgcn4toOz0Qy_o0Pd9nNxPCg+icxQa1Lep5PyOtQ@mail.gmail.com">
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<div>Hello Terre;</div>
<div>I thought I saw this type of image before and we had a
similar problem with our LSN process, see image below.</div>
<div>It turned out that with our setup we were having a reaction
with residual that would react when we vented the tube. This
<br>
</div>
<div>reaction would cause particles to fall ( rain ) on the
wafers when the tube was vented and being unloaded. We had
talked <br>
with Bob Hamilton at Berekley while visiting there and noticed
his LPCVD setup and his solution before we noticed the <br>
</div>
<div>same problem with our LPCVD. After installing the fix we
did not have this issue anymore.<br>
<br>
The solution is to provide a very limited small low flowing
path around the gate valve so that when the gate valve is
closed <br>
</div>
<div>( such as during tube vent ) the tube still has a small
draw on it pulling any reactions toward the pump and away from
the <br>
</div>
<div>wafers. If you have this type of bypass already, the only
thing would be to confirm that it is still working I guess. We
had a <br>
</div>
<div>pressure gauge installed next to this to confirm that it
was working and not plugged. We would see a pressure change <br>
</div>
<div>that indicated it needed cleaning soon. <br>
</div>
<div><br>
</div>
<div>Regards, Tony W.<br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><img src="cid:part1.ADB34741.D5C6E3C9@stanford.edu"
alt="image.png" class="" width="357" height="176"><br>
<br>
</div>
<div><br>
</div>
<div><br>
</div>
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<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Aug 3, 2021 at 11:20
AM Terre Briggs <<a href="mailto:terreb@umich.edu"
moz-do-not-send="true">terreb@umich.edu</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Hello All,
<div> We are currently having film quality issues with
our LPCVD Low Stress Nitride, HTO and Nitride films.
Without getting into all of the details just yet I am
sharing with you some SEM images. The anomaly, as our
furnace manufacturer describes it, are what look like
spheres, or bubbles on the surface of the films. We are
pretty confident that the spheres are only on the surface
and not down into the film itself.</div>
<div>It is very random across the wafers and across the
wafer load. After further processing, the spheres come off
and leave behind a divot, or crater on the surface. This
can also be seen in the SEM images.</div>
<div> My question is, has anyone ever seen anything like
this with any of your LPCVD films? I have been working
with Tempress for the last several months to resolve the
issue, but they have never seen anything like this, and so
far we have not made any progress in determining the
source. Any help would be appreciated. </div>
<div><br>
</div>
<div>Thanks.....Terre</div>
<div> <br>
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<div dir="ltr">
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<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">
<div><font><font>Terre Briggs</font></font><br>
</div>
<div><font><font>Engineer in
Research Sr.</font></font><br>
</div>
<div><font><font>Lurie
Nanofabrication Laboratory</font></font><br>
</div>
<div><font><font>University of
Michigan</font></font></div>
<div><font><font>1301 Beal Ave.</font></font></div>
<div><font><font>Ann Arbor, MI 48109</font></font></div>
<div><font><font>734-320-4470</font></font></div>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
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