on 12/5/01 11:01 AM, mems-talk-request@memsnet.org at
mems-talk-request@memsnet.org wrote:

Sorry if I'm late on this, but here goes:

I recommend that you consider using Ti/Ni for the seed layer instead of
Ti/Au. The Ti provides an adhesive layer to SiO2 or glass, and the Ni
provides a nice surface for the plated gold to stick to. Without something
over the Ti it will oxidize, and the plated gold will flake. The nice thing
about using Ni instead of Au is that you can then selectively etch the seed
layer without worrying that you'll take off too much of your plating. I use
HF:HNO3:H2O at 1:1:10 (it takes off both the Ni and the Ti in under a
minute), which seems to have no effect on the plated Au.

That said, I have no idea why the etch you're using didn't work. If you need
to do it the way your doing it, maybe you could heat it up to 70-80 C.

Best regards,
Jordan

> Message: 6
> Date: Wed, 5 Dec 2001 14:25:34 +0800 (HKT)
> From: mawei 
> To: mems-talk@memsnet.org
> Subject: [mems-talk] seed layer for electroplating gold
>
> Hello, everyone,
>
> A problem happened when I did my electroplating gold: Before I do the
> electroplating, I sputtered a layer of TiW800A/Au2000A for seed layer. And
> the I used the thick PR to be the module for plating gold. After finished
> the plating, I removed the PR, and want to remove the seed layer also. The
> problem happened when I used KI+I2+H2O to etch the seed layer: Gold. I can
> never etch them away clearly. How does it happen? Is it possible that
> sputtering gold can't be etch by KI+I2+H2O afer being covered by PR or
> being dip in the solution for electroplating?
>
> Thank you for your attension.
>
> Best regards,
>
> Vickie