ALERT: BOTTLE 2 OF THE 5% 495k PMMA SPINS OUT OF SPECIFICATION THICKNESS.

[James Conway]

Greetings 5% 495K PMMA Users ,

I just tried to spin some Si wafers with 5% 495K PMMA and had 
difficulties pressing through a filter in a syringe and found the spin 
thicknesses re much greater than specification.   1960 RPM should give 
me about 300 nm and I am obtaining ~480 nm with very large variation 
across one wafer and from wafer to wafer.

The material may have become gelled or hydrolysed from exposure to water 
vapor, breaths, or other contaminations or it may be a odd batch from 
our suppliers.
I will look further into this Monday afternoon looking into this issue 
more closely and track back to batch lots.

I recommend you spin up two wafers with the same spin speed and then 
measure on nanospec and adjust your speed to obtain target resist 
thicknesses.
Users working with this material are requested to report their spin 
speed thickness data to me by email to jwc at snf.stanford.edu

Thank you for your support!

James Conway
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