Fwd: Etching ZnO in pquest during contamination period

Mary Tang mtang at stanford.edu
Mon Oct 31 11:05:21 PDT 2011

Hi Jonathan --

Apologies for the delay in response.  There's been a lot of discussion 
about this particular request as well as how to better respond to the 
more difficult SpecMat questions, like this one.

SpecMat requests that require discussion will be reviewed every Thursday 
at 2:30 -- which is now a standing staff meeting where hardware as well 
as process changes are presented.

As for your specific request, the issue at hand is that the PQuest does 
not really belong to SNF, but to the III-V device community.  Jim 
McVittie is both our etch and contamination expert -- and he has been 
following up with the III-V faculty on this and related concerns.  I 
don't believe he has a definitive yes or no from them as yet, but fees 
unlikely they will be satisfied with a wet chamber clean.  The problem 
with the PQuest is that the system design is such that the chamber walls 
actually play an important role in the chemical reactions so a lot of 
caution is exercised over the types of materials allowed in this 
system.   So, the answer is not a definitive "no", but nor is it a "yes".

Near term, please to contact Ed Myers about the ion milling system in 
the SNC lab.  This system was acquired to etch materials just like this.

Long term, this is just yet more justification for having this sort of 
capability at SNF.


On 10/31/2011 10:20 AM, Jonathan Mailoa wrote:
> Hi Mary,
> Two weeks ago I sent this etching permission request to specmat. I am
> wondering if you have a timeline on when I'll possibly know the result?
> I would also like to know if I have any option for ZnO dry etch (sputter or
> RIE) which will be allowed.
> Best
> Jonathan
> ---------- Forwarded message ----------
> From: Jonathan P Mailoa
> Date: Thursday, October 20, 2011
> Subject: Etching ZnO in pquest during contamination period
> To: specmat at snf.stanford.edu
> Cc: gyama at snf.stanford.edu, Gary.Yama at us.bosch.com, jpmailoa at gmail.com
> Hi,
> I am thinking of etching ZnO thin film (on quartz substrate) with
> polystyrene microsphere as the etching mask. I am thinking of using
> pquest for this process, since it is the only Cl-based gold
> contaminated etcher available at SNF. (I have been informed that
> F-based etchants won't work so well)
> I have previously talked to Jim McVittae about this, and I have been
> informed that the resulting compound, ZnCl2 is considered a
> contaminant for GaAs users (Zn contamination), and as such ZnO is not
> desired in the pquest. I have also ben made aware that pquest has a
> special rule, where F-based gas is only allowed during the last week
> of the month, since it is considered contaminant.
> I am wondering if I will be allowed to etch my ZnO using Cl-based
> etching gas during this contamination period, where users are allowed
> to use F-based gas?
> Best
> Jonathan

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

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