I think you will find the thickness varies quite a lot, if you have so many
dimensions within one sample. The current line will crowd near the opening of
the features, depends on the size, aspect ratio etc. so, you probably will find
the smaller feature is filled much quicker than the large ones. Also, bear in
mind, your seed layer is very thin, the resistance within the seed layer can
play a significant role in it.

Hope it is useful.

Yingtao

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On
Behalf Of Pradeep Dixit
Sent: 03 July 2009 10:25
To: General MEMS discussion
Subject: [mems-talk] Metal electrodeposition rate

Hello All,

I would like to check some thing with you.

During through-resist electroplating, does metal deposition rate depend
upon the opening dimension of features?

I am trying to electroplating 8 um thick copper structures. resist mold is
12 um thick AZ9260. Seed layer is 30 nm TiW/ 300 nm Cu.

features are circular vias and have relatively large variation in diameter.
20 um vias are besides 100 um vias and 500 um vias.

Electroplating type: DC, 5 mA/cm2 current density

I want to know in advance:

will the electroplated thickness be same for all feautures (20 um, 100 um,
and 500 um) ?

OR

500 um diamter vias will be plated faster .

Your opinion will be appreciated.


Thanks,
Pradeep