Hi Nidhi,

You may use ion beam milling but the problem is selectivity of gold is more
compared to platinum. Even if you have very thick resist, erosion during
milling process may cause transfer the resist profiles to gold.

You may try the following options which has very good selectivity for Pt
compared to that of gold.

1. Piranha etch soultion was found etch Pt at a greater rate than that of
the gold. It is roughly about 2- 3 nm/min. Gold is almost unattacked by
Piranha.

2. You can also try SF6+O2. The etch rate is twice that of the previous one
(about 7 - 10 nm/min). Gold was almost insensitive when subjected to these
gases.

3. You can also try CR-14. I have not tried this one but some say it works
and have good selectivity for Pt.

Hope this information helps.

Regards,
Prasanna

On Fri, Jul 31, 2009 at 10:22 AM, nidhi maheshwari wrote:

> Dear All,
>
> I have a stack of chromium/platinum/gold (20nm/20nm/200nm) onto glass.
> I need to pattern and etch it to make electrodes. Process requirement
> is such that I can not use lift-off process for the same. Can anyone
> please suggest a method by which I can etch Platinum without affecting
> gold on top of it. As far as I know aqua regia etches gold very fast,
> so I can not use that for etching platinum. For dry etching we have
> CF4 and SF6 gases available. Can these be used for etching platinum?
> Any suggestions on the recipe for dry etching using these gases would
> be very helpful.
>
> Thanks and regards,
>
> Nidhi

--
Thanks & Regards,
Prasanna Srinivasan