Dear Crayon Fu

You can bake PR at 100 - 110 C (for 60 mins) instead of 130 C.  May be your
baking process at 130 C is hardening the PR. At 130 C you are very close to
the resist burning temperature and it becomes almost impossible to remove it
later.

regards,

Samadhan Bhaulal Patil
INESC Microsistemas e Nanotecnologias,
Rua-Alves Redol, 9,
1000-029, Lisbon, Portugal
url: www.inesc-mn.pt
(m) +351-936623294


----- Original Message -----
From: "Yang Fu" 
To: 
Sent: Monday, March 30, 2009 6:39 AM
Subject: [mems-talk] air-bridge fabrication problem


> Hi All,
> I am having some troubles with fabrication air-bridges on Si. The
> dimensions
> of the air-bridges are: height 1.6um, length 90um, width 20um. I use
> double
> layer AZ5214 and electroplated gold. My process is as follows: patten
> first
> PR layer--> evaporate Ti/Au seed layer--> patten second PR layer-->
> electroplating gold (~1.8um thick)--> AZ300T or NMP to strip PR.
>
> The problem is that bubbles appear after the second PR layer baking(90deg,
> 2min). I have to do a long hard bake(120deg, 30min) for the first PR layer
> to prevent these bubbles. But it would be very difficult to remove the
> first
> hard baked PR layer in the last step. The air-bridges won't release. Is it
> because the first PR layer has been baked too long? Or the AZ300T just
> could
> not squeeze through the 1.6um slit to touch the PR? Thank you for the
> input!
>
> Crayon Fu
> University of Virginia