Proposing a test on compatibility of fluorine and chlorine chemistry

Jim McVittie mcvittie at snf.stanford.edu
Thu Sep 15 13:59:14 PDT 2005


Nickolai,

I guess I disagree with your statement that there is no solid data
characterizing the influence F on Cl based etching process. I have been
going to plasma etch talks for over 25 yrs and I have heard many talks
over the years where data has been presented on the decrease in Cl based
etch rates in the presence of leftover F on the reactor walls.  In fact,
last week at the monthly bay area plasma etch user meeting in Santa
Clara, there were 2 talks, which discussed this issue regarding Si
etching. In addition, there will a number of talks on the influence of
chamber conditioning on etching at the upcoming AVS mtg in Boston in
late Oct.  However, I agree that we have not put any effort into
quantifying the issue in any of etchers in SNF. I did purchase an
optical spectrometer sometime back specifically for looking chamber
conditioning issues.

Your proposed experiment is similar to what Jim Kurger and I have
discussed in the past.
You propose to do the comparison on final etch results. I think it would
better to initially focus on quick real-time measurements, such as
optical emission lines and etch rate. And then to confirm the results
with SEM images of the etch results. For the data I have seen from other
groups, if the emission and etch rates look good, I would be very
surprised if the etch profile and roughness are off. With optical
emission, one can evaluate the plasma during the different conditioning
steps and hopefully determine how long to run a conditioning step. As
for the F exposure, I would run it a factor of 5 to 10x longer than the
expected etch process to give us a safety margin and to make the
response larger and easier to see.  I would look at both low and high
power processes. As for pressure, I would run at the highest pressure
likely to be used since free radical F concentrations tend to increase
with pressure and the Pquest does have any ion bombardment.on the
chamber wall.

I am willing to works anyone who wants to do this study.

Jim


Nickolai Belov wrote:

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