[labnetwork] STS DRIE Multiplex Lip Seal failures

[LaFleur, David W]

Hi Mark,

We have an STS MP0579 ICP which uses the lip seals. It is used mostly for silicon and SiO2 etches with O2 cleans between uses. Most of our Bosch processes are run on SPTS Rapier which uses an ESC. That has its own set of issues. We find the lip seals don’t last more than 2-3 weeks in our system. Our chamber o-rings usually go for 2 months at best. I was thinking of changing to a kalrez o-ring and always wondered if they made a Kalrez lip seal. One suggestion on how to make them last longer is make sure they don’t get exposed to any solvents like Isopropyl when you are installing them. I want to say I am not happy with the longevity of the lip seals either and maybe we need to bring this to the attention of Orbotech/SPTS. Maybe they have a solution. Other than that they are good tools, very reliable, and heavily used here at Harvard. Because they are so heavily used with so many processes we find a biweekly chamber clean and lip seal replacement works well for everyone. This is why I have just lived with the lip seals as they are.

Regards,

David LaFleur
Equipment Engineer
CNS, Harvard University

From: "labnetwork-bounces at mtl.mit.edu" <labnetwork-bounces at mtl.mit.edu> on behalf of Mark Weiler <mweiler at andrew.cmu.edu>
Date: Tuesday, March 5, 2019 at 3:44 PM
To: Fab Network <labnetwork at mtl.mit.edu>
Subject: [labnetwork] STS DRIE Multiplex Lip Seal failures

Hello Everyone,

We have gone through seven new lip seals purchased form Orbotech/SPTS.  They are often failing before we even finish qualifying the system, or within a month thereafter.

Our our process is stable with power and parameters not deviating over the past decade.  However, I ordered the most recent batch of lip seals because the wafer seals we had been using were coming out with black residue after only a few runs… however, the current ones do the same.  Not only have the lips seals disintegrated, but the chamber lid o-ring and bottom ceramic spool o-ring have also failed with black rubber material shedding off.  It’s as if they are made of Buna and not meant for this application.

Our process is typical Bosch with 100 sccm C4F8 and 20 sccm O2 for etching switching off with ~50 Sccm SF6 for passivation at a processing pressure of 15 mTorr, Coil power 600-800W,  Platen power 100-150W, Bias voltage 50-100v (up to 200 peak-to-peak), Platen temp at 19 degrees, Lid temp 41 degrees.  Qual wafers are new bare Silicon.  Etch rates are normal and stable with 10+ years of data…. we just can’t complete the work due to failing seals.

Our chamber base pressure is between 1E-8 and 5E-8 Torr each morning.  When we put in a brand new seal and run only the LUR, it passes with 0.00 mTorr/minute leak rate.  That jumps to 3.00 mTorr/m after only 30 minutes of the SPTS recommended O2 Clean… then rises as time and more runs progress.  Wafers are coming out with black rings on their backsides.

This should not be happening, and I believe it is due to incorrect material of the lip seals and o-rings.  I am pinging the network, though, to see if there might be a parameter change we need to effect that may assist us.

Have any of you seen this before?

Best regards,

Mark

________________________________________________________________

Mark Weiler
Equipment & Facilites Manager
Clair and John Bertucci Nanotechnology Laboratory
Eden Hall Nanofabrication Cleanroom
Carnegie Mellon University
P:  412-268-2471
http://www.nanofab.ece.cmu.edu<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.nanofab.ece.cmu.edu&d=DwMGaQ&c=WO-RGvefibhHBZq3fL85hQ&r=6eLRBFWstHA_77uCRuGQiAtV9vZWeQjYS4oSMBfEHZE&m=GZ5yf4iHmJa34tuDFePywye54bw-ac2pvX333zI9bnA&s=ZH-JLOPgpC2A-fi8K9m7di3gfZlrsVgsRXshO9n5YnI&e=>


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