Novak,
Another couple of materials you may want to look at would be AZ100nXT
(negative tone resist) and AZ50XT (positive tone). Both of these are
available from AZ Electronic materials, and I have been able to achieve
single coat processes with either of them in excess of 100um.
You may especially have luck with the negative tone material, since is
undergoes a crosslinking reaction and should be less susceptible to
basic solutions. Positive novolak materials (such as the AZP4620/9260
and AZ50XT)tend to be vulnerable to high pH (the developer for these
materials is a basic solution, and positive resists are never totally
resistant to the developer - its really just a "relative"
solubility/reaction rate).
Additionally, AZ-EM has their PLP line (-40 and -60) which is especially
created for gold bumping.
Best Regards,
Chad Brubaker
EV Group invent * innovate * implement
Technology - Tel: 480.727.9635, Fax: 480.727.9700 e-mail:
[email protected], www.EVGroup.com
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Novak Farrington
Sent: Wednesday, November 30, 2005 5:32 AM
To: [email protected]
Subject: [mems-talk] Recommendation for Gold bump process
Hi all,
could anyone recommend a combination of thick photoresist (~65um but
thinner
would be OK as I could use a multilayer application) and commercial gold
electroplating bath which work well together? The electroplated gold
needs to
be around 50um for a 'bump' type process on a GaAs substrate.
I've had experience in the past with a cyanide based bath (puramet 402)
but this
seemed to be incompatable with most common resists, showing the usual
documented
problems.
For this reason I'm open to using either sulfite or cyanide based
electrolytes.
I was thinking about using BPR 100 (possibly with thinner) or a
multilayer
AZ45xx/AZ92xx resist.
>From some of the publications I've seen, the sulfite electrolytes
exhibit a
rather high pH (up to 9.5) which is rather worrying - from experience,
to what
degree does this affect the photoresist?
