Hello Ramzee

What materials are you using to make the comb device? What exactly do you mean
by only 1um of clearance.

If you are trying to create a 1um high space under your device (but no deeper)
you can try the following. Our customers have had great success building devices
with uniform spaces as little as 200nm underneath them as follows. There is no
reason you can not go even smaller.

1. make a thin layer of oxide on the silicon wafer
2. add a thin layer of polysilicon, in your case 1um thick.
3. pattern the polysilicon and fill the spaces with oxide to create etch stops
to define the shape of your cavity.
4. add your device material on top and pattern it.
5. remove the polysilicon using xenon difluoride.

We have done this with very thin layers of poly and undercuts typically on the
order of 30um to 100um using oxide as the etch stop material. Xenon difluoride
has a high selectivity to most materials over silicon and does not attack the
most common metals, for example it does not fog Al and has better than 1000:1
selectivity over oxide.

If you have any questions or would like to try something out please get in
contact with me.

David Springer
XACTIX, Inc.
[email protected]

 >>  Could you please let me know the fabrication procedure
 >>  for the cantilever combs in the linear comb device?
 >>  how can we fabricate them on a Si wafer with a
 >>  clearance of just a micron with the wafer surface..
 >>  Please do respond.

 >>  Thank you very much.

 >>  Ramzee


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