Hi Morten,

the structure will stay in vertical position, so i should not have
problems related to gravity.

I think gas-phase etching is a very good possibility. Does someone know
some etchant for SiGe which will preserve the Si layer ?

Thanks,
Andrea

> Hi Andrea,
>
> Before trying to make this be sure to spend an hour with a structural
> mechanics simulation to determine how much the structure will bend
> simply due to gravity. I have a very long (2000µm), thin (1µm)
> cantilever, which will drop to the floor below if not hung vertically.
> With a 2000/1 ratio, the drop is on the order a couple of thicknesses.
> Comparing to your numbers it seems you're in the same ballpark. I'm
> guessing you will need support pillars to avoid this.
>
> Of course, in addition to this, it might be very hard indeed to perform
> such a large underetched area using wet etching. Perhaps gas-phase
> etching might be an alternative?
>
> Best of luck
> // Morten