HgTe/CdTe in Raith

Ed Myers edmyers at stanford.edu
Thu Apr 22 14:48:22 PDT 2010


I think we have to figure out how to process these materials.  I'm 
not sure I follow Mary's logic of the Raith process, but if James is 
willing then it should be OK.

As for the MRC, we probably have been too cavalier about what ends up 
in the diffusion pump oil and how it is handled.  I think we should 
talk with the maintenance staff and make sure they understand there 
is more than likely hazardous materials in the oil.  We should also 
look at putting the system under a routine maintenance program.  I'm 
not that familiar with the tool, but it seems like there are some 
consumable components we should change out on a regular basis (and 
consider hazardous).  I had a talk with Jim Kruger and I though he 
was going to write up some suggestions.  One part involved how to do 
a wet clean and add some foil to capture some of the sputtered material.

Irrespective of approving this material, which I think we need to do, 
we should also come up with a better procedure for how to maintain the MRC.


At 07:53 AM 4/21/2010, Mary Tang wrote:
>Hi all --
>I don't believe there is any reason that he should not be able to 
>process these materials in the Raith, since the temperatures would 
>not be expected to be very high. It isn't likely the beam would be 
>directed at the material itself, but just the resist on top. And I 
>can't imagine the vapor pressure would be higher than for resist.
>As for the MRC request, I caught part of the conversation between 
>Jim McV and Jim K about this -- at that time, I think both were in 
>agreement that if they had their own complete, dedicated set of 
>quartzware and shields, we could minimize the possible risk of 
>off-gassing in subsequent runs. The concern, I believe, was not the 
>individual piece or two, but coming up with a broader, workable 
>solution in case this work expands or similar materials are 
>introduced. I think the one thing that had not been resolved was how 
>to handle the diffusion pump oil (not a user issue, but a 
>maintenance staff safety concern.) I suspect the safest solution 
>(unless we ban the material from etchers) would be to require staff 
>wear PPE while performing pump oil changes.
>What does everyone else think?
>Matthias Baenninger wrote:
>>Dear Special Materials Committee,
>>In addition to my inquiry about using the MRC etcher (see separate 
>>email), I'd also like to check if I could use the Raith to do ebeam 
>>lithography on HgTe/CdTe devices. The material is identical, i.e. 
>>Hg_0.3Cd_0.7Te/HgTe heterostructures grown on a CdTe (Zn 4%) 
>>substrate. Spinning of the resist and developing would be done 
>>externally, so the device would be covered in PMMA during the 
>>entire process done at SNF.
>>Many thanks,
>>Matthias Baenninger
>>Coral login: mbaennin
>>Matthias Baenninger, PhD
>>Goldhaber-Gordon Group
>>Stanford University
>>McCollough Bldg., Room 224
>>476 Lomita Mall
>>CA 94305-4008
>>Phone: +1 (650) 723-5892
>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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