[labnetwork] STS DRIE Multiplex Lip Seal failures

[Roy Cork]

Hi Mark,

We (DTU Nanolab of Denmark) are not running the BOSCH process in our SPTS mechanically clamped ICP but we are etching III-V materials at elevated temperatures of up to 180°C on 100mm substrates.

I would estimate that when the tool was initially installed the Viton lip seal would last for approximately 6 months and then become either brittle or etched and needed changing (HELUR became too high >15mT min).

We were recommended by SPTS to change over to a new material called F70A which has a temperature range specified at -55°C to +225°C. The material is blue in colour and since the change we find our lip seals can easily last for one year or more.

The black ring on the back of the wafer doesn’t sound too good. Some other things you should also look at is the flow of He and pressure, also the flow and cooling capacity of the chiller in case this is not the original that was shipped with the tool.

If you need the part number from SPTS for the F70A 100mm lip seal I can dig it out for you, just let me know.

Best regards
Roy Cork

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Mark Weiler
Sent: 6. marts 2019 01:05
To: Fab Network
Subject: Re: [labnetwork] STS DRIE Multiplex Lip Seal failures

Correction...

In my haste to write something up and get out the door I mixed up the gas is in the problem description.


Our process is typical Bosch SF6 and  O2 for etching .... switching off with C4F8 for passivation...


Mark

Mark Weiler
Equipment & Facilities Manager
Claire and John Bertucci Nanotechnology Laboratory
Electrical and Computer Engineering | Carnegie Mellon University
5000 Forbes Ave., Pittsburgh, PA 15213-3890<x-apple-data-detectors://3/1>
T: 412.268.2471<tel:412.268.5430>
F: 412.268.3497<tel:412.268.3497>
www.ece.cmu.edu<http://www.ece.cmu.edu/>
nanofab.ece.cmu.edu<http://nanofab.ece.cmu.edu/>

On Mar 5, 2019, at 18:42, Mark Weiler <mweiler at andrew.cmu.edu<mailto:mweiler at andrew.cmu.edu>> wrote:
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


[cid:image001.png at 01D4D3F5.14205AE0]<https://www.linkedin.com/in/marksbasics>

_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20190306/a6157359/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 720 bytes
Desc: image001.png
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20190306/a6157359/attachment.png>