Jukka,

Ni oxidizes easily. It is estimated that on RT it forms an oxide layer that
interferes with plating within few minutes, at 50C in less then one minute.
As it is difficult to process Ni substrate in short time after deposition
and keep it from oxidation you need to apply an acidic rinse, e.g. 15% HCL
(30% diluted with DI water 50/50) for app. 1 minute - this must be
established as a function of oxide thickness), followed by short rinse
(app.10 sec) at RT with a dilute sulfite solution or other solution
depending on the type of your gold solution at pH adjusted to that of Au
plating solution or slightly more acidic (If your Gold is alkaline solution
it becomes more dificult to electroplate Ni - the more alkaline solutions
form faster Ni oxide). That is to minimize the contamination of Au solution.

The process is achievable but it requires ease of handling and practice. To
this end we offer equipment that is designed to minimize uncertainties in
timing and wafer handling. Our IKoClassic is an ideal tool as it enables
precise setting and easy optimization of processing parameters including
wafer preparation and electroplating. More details can be found in our
website www.fibrotools.com.

Sincerely,

I. Kadija
President, CEO
ECSI


----- Original Message -----
From: 
To: 
Sent: Monday, January 03, 2005 4:28 AM
Subject: [mems-talk] Plating Au on Ni.


Hello,

We are making process where we would like to plate gold features using
thick PR-mold. Process we had in mind was following:

1.    Evaporate Ni layer on GaAs-wafer.
2.    Make thick PR-mold
3.    Plate Au-trough mold on Ni
4.    Remove PR
5.    Etch Ni away using plated Au as a etch mask

However we have problems with plating on Ni. It just is not plating
anything. Should we try to make some pretreatment to Ni before try to plate
Au?

We have fresh and clean chemical with correct pH. Also plating Au on Au is
working correctly. We are making our plating with Enthone Nuronex 309B
plating solution (should be same stuff than Microfab Au150).

Best regards,
Jukka Viheriälä

***********************************************
Jukka Viheriälä, Researcher

Optoelectronics Research Centre
Tampere University of Technology
P.O. Box 692
FIN-333101 Tampere, Finland

Tel.: +050 595 4147
Fax  +358 3 3115 3400
Email: Jukka.Viheriala@orc.tut.fi



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