Request to use lampoly or p5000 to etch semi-clean wafers

Nahid Harjee nharjee at
Fri Oct 9 12:55:49 PDT 2009

Thanks for the prompt reply.


On Fri, Oct 9, 2009 at 12:00 PM, Mary Tang <mtang at> wrote:

> Hi Nahid --
> It's agreed, your request is approved for both the poly etch chamber in
> p5000etch and in lampoly, with the EBR considerations you describe.
> Thanks!
> Mary
> Nahid Harjee wrote:
>> SpecMat,
>> I am designing a process to fabricate single crystal silicon cantilevers
>> that are 3 um thick. The narrowest cantilevers are 14 um wide and have 4
>> "legs" at the clamped end that are 2 um wide. I am trying to select a tool
>> to etch the 3 um of silicon to define the cantilever that will produce
>> straight sidewalls. In the past, I have used stsetch to define wider
>> cantilevers. However, I am concerned that the scalloping resulting from this
>> tool will make it difficult to etch the 2 um legs of the new design. Thus, I
>> am writing to propose that I perform this etch with HBr/Cl2 chemistry in
>> lampoly or p5000. What makes this process non-standard is that my wafers
>> will be semi-clean at this point. The step prior to defining the cantilevers
>> is deposition of 1500 A of Al in gryphon which is then patterned with a wet
>> etch in Al-11. During the Si etch, the Al will never be exposed to the
>> plasma (it will be covered by 3 um of resist). However, there is a chance
>> that there will be trace Al on the exposed Si from the Al-11 bath. At the
>> most recent process clinic, Keith Best raised the point that there may be
>> exposed Al in the EBR region of my wafers. In order to minimize this
>> possibility, I can use 5 mm EBR for the Al litho and 2 mm EBR for the
>> cantilever litho, ensuring there's a buffer of 3 mm of resist with no Al
>> below it.
>> I look foward to hearing your decision on the proposed process or if there
>> is a tool that is better suited for this process, I welcome any suggestions.
>> Thanks,
>> nh
>> --
>> Nahid Harjee
>> Ph.D. Candidate
>> Electrical Engineering
>> Stanford University
>> 408-761-8651
> --
> Mary X. Tang, Ph.D.
> Stanford Nanofabrication Facility
> CIS Room 136, Mail Code 4070
> Stanford, CA  94305
> (650)723-9980
> mtang at

Nahid Harjee
Ph.D. Candidate
Electrical Engineering
Stanford University
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