SpecMat Logsheet, Dec. 5, 2006
edmyers at stanford.edu
Mon Dec 4 15:42:01 PST 2006
I have a conflict for tomorrow's meeting. We only have a couple of
items, so I am canceling the meeting.
1) Bismuth/Antimony Telluride is not listed in the standard
materials, and I would like to know if I can use it in a limited way
in the lab. The material would be brought into the lab as patterned
films on the order of 10 um thick on 4 inch silicon wafers or smaller
chips. Initially I will be doing SEM work. Later I will be
depositing metals, thereby encapsulating the Bi/Sb-Te, and patterning
the metals. I do not know the specifics of the equipment that would
be used but they would be the 'contaminated' class of tools.
Recommendation: The MSDS seems viable. There is concern about
vapors which can form by water, acids or oxidizers. My initial
impression is the request can be approved, but we should get more
detail the process flow first.
2) I am requesting approval of the following: 1. application of
polycarbonate plastic film in Innotech. 2. Bring in outside wafer
after CMP. The surface at this stage surface contains SiO2 and
carbon. 3. SiO2 etch in drytek 4 of a wafer having both SiO2 and
carbon on the surface. 4. PECVD SiO2 dep on a wafer that has carbon
nanotube exposed. My process flow is the following: 1. Silicon
Nitride deposition on Si wafer (clean) 2. Litho to pattern the
nitride 3. Ni (10nm) and Fe (3nm) deposition through a polycarbonate
membrane and SS shadow mask in Innotech. (cont) 4. PECVD SiO2
deposition (cont) 5. CMP (outside lab) 6. Drytek 4 etch of SiO2
(cont) 7. PECVD SiO2 dep (cont) 8. Cr dep (cont)
Recommendation: Approve the process. The question I have regards
post-CMP cleans. Do we have a recommended clean process for each
equipment category? Any suggestions.
3) I need to etch silicon isotropically with a high selectivity to
oxide and nitride. I was planning on doing it in the new XeF2 but it
is a gold-contaminated equipment. After this step, I need, among
other things, to do wet oxidation and DRIE. Is there any way to
decontaminate a wafer that has gone through the XeF2 machine or
should I just drop the idea of using XeF2 in this process (in which
case are there alternatives to do a highly slective isotropic Si etch)?
Recommendation: The question is, can we use the Xactix as both a
semiclean and gold contaminated equipment? The wafers or samples set
on a removable stainless steel platen. If we dedicate the platens to
the appropriate clean category, can this tool serve a dual
purpose? Initially it was my plan to use the Xactix for all
categories (silicon), but the Xactix VP told me a story about having
gold evaporate off the sample and coat the chamber. The etch process
is exothermic and under certain conditions, vaporization of the
material is possible. I think this has a low chance of occurring. I
would like to suggest we take the risk, fabricate multiple platens
and open the tool up to both semiclean and gold contaminated samples.
Please respond with your comments by Thursday, Nov. 14th.
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