SpecMat Logsheet, 10/12/05

Mary Tang mtang at snf.stanford.edu
Mon Oct 10 16:41:35 PDT 2005

Hi all --

I agree with Ed on items 2 and 3.  As for #1, I believe that it would be 
possible to do this at wbsilicide, if the pots were decontaminated with 
5:1:1 H2O:HCl:H2O2 beforehand.  Actually, he could probably do this at 
wbdiff, but given the station is so busy, I'd be less inclined to 
approve it there, as other people would not be able to use the station 
while he's doing this.  If he does this at wbsilicide, he's less likely 
to annoy others.  Any pot that is filled with non-standard acid mixture 
must be clearly labeled.  The wbsilicide station should be put down as 
"Yellow" while it is being used for this purpose.

I don't think there's a serious contamination concern with doing SC1 and 
SC2, since those cleans remove trace organics and metallics which would 
be of any concern.


Ed Myers wrote:

> SpecMat Members,
> Tuesday, 10/11 is our normal SpecMat meeting day.  However many of us 
> will be involved with our visitors from Korea.  I would like to 
> propose we do this meeting by email.  We have three new items to address.
> 1) Jun-Fei Zheng:  Poly deposition on a Vapor Jet Deposition Si3N4 
> film from outside CIS.  Jun-Fei is willing to provide TXRF data to 
> show the film meets our contamination requirements.  The second part 
> of the request is "to avoid H2SO4:H2O2 process as our wafer has never 
> been through Lithographic process and this is what the H2SO4:H2O2 
> mainly for but H2SO4:H2O2 process might destroy the gate quality 
> Si3N4. We also do not see the need for 50:1 HF dip, which is used for 
> clear oxide formed on Silicon during H2SO4:H2O2 process. We believe 
> SC1 and SC2 in combination would be able to address potential 
> contamination during wafer handling and shipping."
> Comments:  The Thermcopoly tube is part of the Clean Equipment set and 
> requires a pre-diffusion clean prior to deposition.  The request is 
> use an SC1/SC2 clean approach instead of the standard pre-diff clean.  
> Is there a bench were we can use SC1 (NH4OH/H2O2/H2O) and SC2 
> (HCL/H2O2/H2O) or will the work need to be done in beakers?
> 2) Ching-Huang: McIntyre ALD Hf02 processing in Semiclean Tools.  TXRF 
> analysis was provided with the request.  The data shows the sample to 
> be above our SemiClean contamination specification for both Fe and Ca 
> (along with S).  Do to peak overlap the levels of Ni, Co and Cu 
> (possibly Cl) could not be determined.
> Comments:  I do not think we should approve the request with this 
> level of contamination.  I feel there should be an effort made to 
> reduce the contamination level in the ALD system before we assume the 
> contamination risk.
> 3) Mike Weimer:  Limiting CF4 Etchs in pQuest.  Etches using CF4 must 
> contain high amounts of O2. As a guideline (this number is not 
> perfectly strict, but is a good guideline) any etch with CF4 should be 
> ~20% CF4 and 80% O2. Small variations around this % are OK. No etches 
> containing large amounts of CF4 and small amounts of O2 are allowed.  
> This basically eliminates etching of Si3N4 and SiO2 with CF4.
> Comments: I do not think we should accept this proposal as presented 
> because it is to confining.  I attended the meeting where this 
> proposal was developed.  It is based on seen non-responsibility in the 
> GaAs etches.  From the data that was presented, I was not convinced 
> all the non-reproducibility were caused  by the CF4 etches.   The GaAs 
> community was not willing to support testing of the memory effect in 
> the chamber as the gas chemistries are switched.  The work was 
> volunteered at not burden to the GaAs community.  I did volunteer to 
> email the pQuest community with any SpecMat request that come in.  
> This way they can voice their concerns early in the approval process.

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at stanford.edu

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