Thanks Bill,

Thing is, I was really hoping I'd get a "no way" or "yay go for it"
kind of answer, as the experiment would take half a day, which right
now I don't have.

Instead of chromium I could use tungsten, which also doesn't etch in
the phosphoric acid, while aluminum won't etch in hot H2O2, as far as
I know. Would that be a better electro-couple from the POW of
undercut? For the record, I don't need to remove the inorganic mask
after the last aluminum etch step.


best

m

On 1/4/12, Bill Lytle  wrote:

> Ned,
>
> That should work, although you might experience some undercutting of the
> aluminum due to the galvanic coupling of the Cr with the Al. There is no way
> to determine how much undercut will occur except experimentally. You might
> also experience some undercut of the Cr when you inititially pattern it
> depending on your Al surface area relative to the photoresist covering the
> Cr. That could be non-uniform depending on how long the etch continues
> before completion.