There can be two problems; as i suspect.

1) Your oxide layer is not completly removed. so your Cr is not going in Cr
etchant.

2) Or u might be using KI based gold etchant.which will not affect the Cr,
but HNO3+HCl based gold etchant (Aqua regia)  will etch Cr very fast.But be
careful for underetching.

How you are depositing top oxide layer?

Best Luck

-abhay Joshi

Research Scholar,
UIniversity of Pune India.


> ---------- Forwarded message ----------
> From: "Andrea Mazzolari" 
> To: "General MEMS discussion" 
> Date: Sat, 6 Nov 2010 21:14:55 +0100 (CET)
> Subject: Re: [mems-talk] Chrome and Oxide
> > Is there a way to etch chrome oxide ? i tried gold etchant as
> > recommended by a memsnet user, but that didn't work.
>
> What do you mean with "gold etchant" ?
> I do not know which gold etchant you are using, i use a gold etchant from
> sigma aldrich, i do not remember the chemical composition, but it has a
> dark red color. Such gold etchant does not etch Cr at all...
>
> Best regards,
> Andrea