Parrish,
I believe symptoms you describe are often encountered with Au seed layer
regardless of the electroplated metal. Typically, the cause is an inadequate
plasma cleaning/descum. An excessive use of plasma on Au seed layer causes
splattering of Au on the side walls of the openings. Consequently, when
electric field is applied the side walls, being closer to the PR surface,
are more exposed to the field then the bottom of the openings/holes. Ones
the plating starts on the walls it is impossible to prevent it. Yes, when
you optimize the plasma cleaning process it does make sense to play with
current mode of operation and other parameters.

Igor Kadija
www.fibrotools.com

----- Original Message -----
From: 
To: "General MEMS discussion" 
Sent: Sunday, May 10, 2009 3:34 PM
Subject: Re: [mems-talk] Gold Post Electroplating; Posts are Hollow


> For the seed layer I do an e-beam evaporation of titanium and then gold.
> After
> developing the KMPR I do a quick RIE descum for 2 min with 100 W, and 10
> sccm
> O2 to make sure I get any latent crud out of the holes.
>
> That second suggestion you mention seems to make the most sense.  My holes
> are
> fairly spaced out.  Also, I am using an anode that is much larger than the
> area
> on the wafer I am trying to plate, and I was worried that the difference
> in the
> anode/cathode area would cause more e-field at the edges of the holes.  Is
> it
> best to have an anode:cathode ratio that is 1:1?
>
> Is this problem just as severe for other electroplated metals or is it
> more
> prominent when electroplating gold?
>
> Thanks for all the suggestions!
> Parrish
>