Dear all members;

I am a new member to this society, and know lettle about the micromachine
and related properties. Currently I am working on a project making small
dimentional cantilever(L/W:10/2-4um) with one end free standing. I have
been using the evaporation method to make cantilever beam, and have tried
various metals: Au, Al, Al/Si, Ni, NiCr and bi- tri-layers of different
metal combination, but none of them were sucessful. What I found out is
that Au is too soft to collapse, Al surface is oxidezed, and any other
hard metal leads to a curling-up beam. Would  anyone please give some
advise related to the following questions? A small hint related to any
question would be appreciatable. I am stacked at the moment and need your
help. Thanks in advance for your help.


1. Has any one made cantilever using Au? Did you found out it is too soft
to make cantilever?

2. What causes the  cantilever beam curling-up using hard metal which is
evaporated?  Is the stress  induced by temperature gredient during
evaporation or the residule stress build-in in the metal?

3. How to eliminate the stress in the beam? is there any way to reduce the
stress without annealing since I am using PMMA as sacrificial layer, which
is unable to be annealed at high temperature.
I have also tried to evaporate at cooling down temperature it did not work
as well.

4. Beams made with bi-, tri-layer metals showed worse results. Beams'
curling-up became severe. Is this caused by the difference of thermal
expansion? Is there any way to reduce this effect? If can make beam
curling-down, it would be very useful for our device. Any body has this
experience?

5. Is the evaporation suitable for making cantilever? I have also tried
sputtering, the result was almost identical. Electrical plating is out of
consideration at the moment. Can any one give some advise?


Best regards,

Jack Luo
Cavendish Lab.