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<div class="moz-cite-prefix">Mark,<br>
UC Berkeley has an extensive process monitoring program.<br>
For many years we have monitored monthly approx<br>
10 dep and 10 plasma etch recipes (plus litho) as well as <br>
run a CMOS baseline process approx annually.<br>
The baseline offered discrete devices down to 0.35um transistors<br>
and modest integration such as multistage ring oscillators.<br>
<br>
We have recently overhauled our monitoring effort and expanded<br>
it to ~35 processes with more integration e.g. rather than just<br>
blanket etch rate, plasma reactors are now monitored with<br>
patterned resist - selectivity and side wall angle are now
measured.<br>
The CMOS baseline continues though it has also been overhauled<br>
and adapted to more generic design rules to enable external
researchers<br>
to design in it.<br>
<br>
The effort is enormous. A senior engineer for design and oversight<br>
of the Quality Monitoring program, a senior engineer for design<br>
and oversight of the CMOS baseline, a junior engineer for short
loop<br>
tests and detailed metrology, and 4 part time student assistants
for routine <br>
processing. All engineers have additional lab tasks - this is not
their <br>
exclusive assignment.<br>
<br>
The pay off is significant. For example, the first successful CMOS<br>
transistor run in our new lab served as certification of:<br>
-DI, N2, and O2 quality as well as sink, SRD, polysilicon and gate
<br>
oxidation furnace cleanliness. Nothing beats an on target flat
band <br>
or threshold voltage. <br>
<br>
Tests of our gate oxide once detected odd traps in the CV curve <br>
- furnace contamination or member 'abuse' was immediately
suspected. <br>
But when the trap levels were identified as Fe - a review of all
tools in <br>
the gate oxide flow uncovered pinholes in the surface of the final
clean <br>
spin rinse dryer (SRD) - (sub surface corroding of the SS)<br>
The SRD was replaced, the sinks RCA cleaned, the furnace quartz<br>
replaced and TCA cleaned - and quality CV curves were recovered.<br>
<br>
We have also added some simple cantilevers with range of<br>
length and width to the CMOS baseline.These structures are <br>
not integrated to CMOS control but are released. Wafer bow <br>
measurements are persuasive - but released cantilevers that <br>
don't curl are convincing.<br>
<br>
I look forward to discussing further at UGIM<br>
<a class="moz-txt-link-freetext" href="http://www.cns.fas.harvard.edu/UGIM2014/">http://www.cns.fas.harvard.edu/UGIM2014/</a><br>
<br>
Bill Flounders<br>
UC Berkeley<br>
<br>
<br>
Mark Walters wrote:<br>
</div>
<blockquote cite="mid:000701cf13bb$596d4860$0c47d920$@duke.edu"
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<div class="WordSection1">
<p class="MsoNormal">I imagine that like most of you, we offer
some standard baseline cleanroom processes for our users to
implement. For example, there is a standard positive resist
process and negative resist process, standard RIE etch
recipes, etc. We’ve done some characterization of these
processes in the past, especially when they were first set up,
but we now want to be more intentional on monitoring these
processes over time to be able to notice trends or problems
before they affect our users.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was wondering if other university
cleanrooms do periodic process monitoring, and if so, what
types of processes and monitoring have you found to be most
useful for you and your users. Do you look at single isolated
processes (e.g., evaporation thickness uniformity) or build
devices that test the integration of multiple processes (e.g.,
MOS devices or TLM resistance structures) or a combination of
both?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Mark D. Walters, Ph.D.<o:p></o:p></p>
<p class="MsoNormal">Director, Shared Materials Instrumentation
Facility (SMIF)<o:p></o:p></p>
<p class="MsoNormal">Duke University<o:p></o:p></p>
<p class="MsoNormal">Box 90271<o:p></o:p></p>
<p class="MsoNormal">Durham, NC 27708-0271<o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="blocked::http://smif.lab.duke.edu/"
title="blocked::http://smif.lab.duke.edu/"><span
style="color:blue">http://smif.lab.duke.edu</span></a><o:p></o:p></p>
<p class="MsoNormal">Phone: (919) 660-5486<o:p></o:p></p>
<p class="MsoNormal">Fax: (919) 660-5491<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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