[labnetwork] Pegasus - Rapier Esc question

[Kevin Owen]

We have 2 Pegasus systems, one 4" and one 6", and a 6" APS, all with 6kV
esc's. Assuming the same software and recipe format, it's in the "leak
check" step defined for each recipe. There should be a warning level and a
fault level. Ours is set for 125 mTorr/min warning, 150 mTorr/min fault. On
the APS, it's higher (200 mTorr/min fault), since that chuck is older and
more worn and we don't get as good leak checks on it. It doesn't really
affect process as long as the chuck and wafer are clean so you are getting
consistent results wafer-to-wafer.

We typically run 10 Torr backside pressure, most recipes are either 10C or
20C (although temperature doesn't really seem to matter for this). With
brand new, shiny ESCs, we've seen anywhere from 10-40 mTorr/min. Leak rates
then slowly increase over time as the chucks wear. With proper care, they
seem to last a few years before it gets uncomfortably high (to me,
uncomfortable is ~150 mTorr/min) and we replace them. Currently, both
Pegasus tools are somewhere in the 40-70 mTorr/min range, and the APS is at
100-120.

I'd say the biggest factor that will affect this is the cleanliness of the
back of the wafer. Many years ago, when our tools were still new, we would
have very regular (probably once per day) leak check failures due to
particulate on the back of their samples. What sort of leak rates are you
seeing? What's your chamber leak rate?

-Kevin

On Mon, Jun 13, 2016 at 2:03 PM, LaFleur, David W <
dlafleur at cns.fas.harvard.edu> wrote:

> To Engineers who maintain Pegasus – Rapier Systems with Esc
>
> Where do  you set your 15 Torr leak up rate pass/fail limit for the Esc.
> Does anyone have success in achieving the factory spec of 50mt/min on a
> 150mm chuck for 15 torr @15degC ?
> What is your max flow you like to see for 15 Torr?
> Thanks in advance.
>
> David LaFleur
> Equipment Engineer
> Harvard University
>
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-- 
Kevin Owen
Senior Engineer in Research
Operations Group, Lurie Nanofabrication Facility
University of Michigan
(734) 545-4014
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