[labnetwork] Need RIE help

[Morrison, Richard H., Jr.]

Well that is great info,

 

Here are my results so far, thanks to all whom have wrote replies:

 

Removed the Teflon ring and the F peak on the plasma scope reduced by
about 30%, the ring shows heavy etch damage, according to STS it is
needed in the system to help confine the plasma

We found out that the "o"-ring that seals the chamber cover is greased
with fomblin grease, changing that out today, data to come.

We will swap out the dry pump for a new one to see if we have an oil
back-stream issue due to a bad seal. One stage on the dry pump uses
Fomblin oil.

All of you have suggested very long O2 cleans so we are going to try
that after the grease and pump change. We are also going to increase the
O2 flow to 125sccm from 50sccm, increase the pressure to 250mT and
increase the power.

 

Any more ideas out there?

 

Rick

 

 

From: Mac Hathaway [mailto:Hathaway at cns.fas.harvard.edu] 
Sent: Friday, July 29, 2011 9:45 AM
To: Mary Tang
Cc: Morrison, Richard H., Jr.; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Need RIE help

 

Hey all,

This is Mac, at Harvard CNS.  Our STS has shown some symptoms of this
due to polymer on the walls coming off in the O2 clean, introducing
fluorine via that route.

When you wrote "the F peak is clipped of in height during the O2 plasma
clean?"  Did you mean it was still there, but shorter?  This would
clearly indicate the F is still there, and the only question is where
it's coming from.

Perhaps a longer chamber clean, with a low-pressure step to spread out
the cleaning plasma, before the stripping runs?...

Keep in mind that an O2 resist strip can gum up your chamber, and cause
instability in your regular etch processes if you're not careful.


Mac

Mary Tang wrote: 

Hi Richard --

A similar problem was observed and diagnosed on one of our O2 ashers by
one of our industrial labmembers who was a plasma etch engineer at HP.
The cause seems to have been trace amounts Fomblin pump fluid coming
back into the chamber -- Fomblin is basically a polymerized freon, so
there's your fluorine source.

Mary





-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
Paul G. Allen Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu



On 7/27/2011 4:58 AM, Morrison, Richard H., Jr. wrote: 

Hi Everyone, 

  

Our facility uses an STS RIE tool (100mm wafers), to etch
Nitrides/Oxides/Ti and resist cleans. I have a big problem when we use
O2 to clean off resist from wafers. It seems that just running O2 plasma
we etch 1000A/min of SiO2. It should be impossible to etch SiO2 with O2
plasma. 

  

In trouble shooting we have done the following, change the Teflon wafer
holder, disconnected the SF6, CF4 and CHF3 tanks and capped the lines,
then pumped the machine down and just ran O2 and we still etched the
SiO2 at 1000A/min. We have a plasma scope and the F peak is clipped of
in height during the O2 plasma clean? 

  

Does anybody have any ideas on what may be going on. 

  

Thanks in advance, 

Rick 

  

  

  

  

Rick Morrison 

Senior Member Technical  Staff 

Acting Group Leader Mems Fabrication 

Draper Laboratory 

555 Technology Square 

Cambridge, MA  02139 

  

617-258-3420 

  

 
_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu
https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork
    

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20110729/6249e909/attachment.html>