Hi Shree,

  I was able to etch through a 675 um Si wafer using a thick AZ resist (I think
it was AZ9260) and doing many, short (several minute) etch steps on an STS
Pegasus DRIE. You'll have to see how short or long an etch you can get away with
- without heating problems. I first etched the wafer without bonding it to
another 6" wafer to improve thermal conduction (cooling). When I got close to
the full thickness of the wafer, I placed another wafer with melted crystal wax
on a hot plate and bonded the two wafers together (so any over etch would not
affect the chamber floor).
I had very large features (cm sized) so I was not concerned about side wall
angle, so sorry, I cannot comment on that. From what I hear, there are many
"knobs" that  can potentially be adjusted to optimize your sidewall angle. Your
DRIE documentation may have some suggestions on which parameters to tune. Good
luck!

Felix
Applied Quantum Technologies, Inc.



On Dec 11, 2012, at 7:02 PM, Shree Narayanan wrote:

> Mr. Lu,
>
> Thanks for the information. I am trying to etch 200u+ deep channels. Does
> crystal bonding work to this depth? I attempted thermal grease but local
> heating effects etched the photoresist away quickly in certain parts. Would
> you be able to comment on the sidewall angle for the structures you had
> etched?
>
> Thanks
> Shree
>
>
> On Wed, Dec 5, 2012 at 3:57 PM, Felix Lu  wrote:
>
>> HI Shree,
>>
>>  Crystal bonding wax applied liberally over the backside of the wafers
>> has worked nicely for me in the past. It dissolves in acetone. You can heat
>> up the bonded wafers after DRIE and slide them apart, then soak them in
>> acetone.
>>
>> Good luck!
>>
>> Felix Lu
>> Applied Quantum Technologies, Inc.
>>
>> On Dec 5, 2012, at 10:36 AM, Shree Narayanan wrote:
>>
>>> Hello all,
>>>
>>> I need to mount a 4" silicon wafer on a 6" metallized carrier wafer, in
>>> order to etch it in a Alcatel deep-reactive ion etcher. I am wondering if
>>> someone has used thermal vacuum grease for this purpose that can be
>> removed
>>> easily at the end. The silicon wafer is patterned with photoresist and
>> has
>>> no other material on it.
>>>
>>> Thanks
>>> Shree
>>> _______________________________________________
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>>
>> ----------------------------
>> Felix Lu
>> felix_lu@yahoo.com
>>
>>
>>
>>
>> _______________________________________________
>> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
>> provider of MEMS and Nanotechnology design and fabrication services.
>> Visit us at http://www.mems-exchange.org
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> _______________________________________________
> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
> provider of MEMS and Nanotechnology design and fabrication services.
> Visit us at http://www.mems-exchange.org
>
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>
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----------------------------
Felix Lu
felix_lu@yahoo.com




_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

Want to advertise to this community?  See http://www.memsnet.org

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http://mail.mems-exchange.org/mailman/listinfo/mems-talk