I have had diffiiculties with AZ4620 too. I thought the poor adhesion was
related to the black silicon etched surface to which I was applying the
resist. I had better adhesion on the unetched surface of a new test wafer.
As per advice from Clairant I tried soft baking on a hot plat, rather than in
an oven. This seemed to result in somewhat better, though less than
satisfactory adhesion.
The final solution offered by Clarient was to precoat the wafer with something
called Barley (sp?), which I didn't get around to trying.
This resist is probably particularly sensitive to adhesion problems due to the
fact it is so thick.
I succeeded in overcoming an adhesion problem with S1813 (much thinner resist)
on Pyrex by first coating the Pyrex with chrome.
>>> [email protected] 01/16/02 02:29PM >>>
There has been a lot of discussion about 4620 recently, which prompts me
to ask a related question:
I have unsuccessfully attempted to use 4620 recently. The problem that
I have had is a "bubbling" of the resist immediately after exposure.
The "bubbles" nucleate in all open areas. The resist sheds in circular
flakes from the open areas - sometimes even before developing. If there
are features surrounded by lots of open area, these features flake off
as well. Has anyone else seen anything like this?
The recipe that I am using is based on recipes from Clariant, recipes I
found on various websites, and exposure tests that I personally
performed:
Hotplate bake at 150degC for 30min
Vapor phase application of HMDS
Apply AZ4620 and spin at 4krpm for 30.0sec
Softbake on hotplate for 200sec at 110degC
Resulting resist thickness = 7.5um
Exposure for 17sec (intensity = 4.5 mW/cm^2) in hard contact with mask
Develop in diluted AZ400K (1:4 AZ400K:water) for 2-3min
Blow dry
I suspect this may be an adhesion-related problem, but would be
surprised considering that some of the affected feature sizes are >50um
and the resist thickness is >5um. I also have tried increasing the
softbake time to get rid of excess solvents, but this has not alleviated
the problem.
One other comment: the exposure dose that I determined to be optimum was
much less than that suggested in the recommended 10um process on the AZ
P400 data sheet. My exposure dose was 76.5mJ while the recommended dose
is 400mJ.
Thanks in advance for any information or suggestions you might be able
to offer,
Jennifer
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