Carmen:
I'm afraid what you encountered is an adhesion problem, adhesion between Au
and Cr. The gold layer normally shall be deposited with adhesion layer in
the same chamber from same run. I assume due to lack of sputtering targets
you did that way. We have various metal targets and work on multi-layer
deposition and patterning routinely. Please contact me if you need foundry
services.
Regards,

Ping Li
Manager of Process Lab
NP Photonics, Inc.
5706 Corsa Ave.
Westlake Village, CA 91362
818-991-7044 Ext. 218
818-991-7128 (Fax)
mailto://[email protected]
http://www.npphotonics.com


-----Original Message-----

Date: Tue, 27 May 2003 23:57:56 +0800
From: Carmen 
Subject: [mems-talk] Problem in gold wet etching by using KI/I2
        mixture
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii

Dear all,

I faced the problem when I tried to use a KI/I2 mixture to etch gold. I
am going to pattern the Cr and Au layers on the silicon substrate, and I
used thermal evaporator to deposit the Cr and then sputter to deposit
the gold. After depositing the gold layer by using sputter, I used a
KI/I2 mixture to etch the gold layer. After etching for about 10 mins, I
saw the gold was completely etched and there should be a shiny Cr layer
under the gold layer after the wet etching. However, there is a cloudy
thin film in light brown color appeared at the bottom of the gold layer
and that layer cannot be etched in the gold etchant. I would like to
know whether you have seen this problem before, and do you have any
suggestion of the reason to cause this problem and what the layer is? Is
that layer caused by some compound generated after the gold etching?
Thank you very much!

Best Regards,
Carmen

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