LithoTalk

[vsoares]

We have been exposing 13 micron thick layers of AZ4562.
We normally let them rehydrate for 3 hours before exposure.
Our developer was out of date and we were not able to get a 90? profile.
After receiving the new developer, we manged one good sample with 30 min rehydration time and 1:4 AZ400K dilution, and were never able to reproduce it. We cannot develop with 1:4 dilution, and even with 1:3 it takes about 14 min and the results are not good.
The film thickness has not changed ( we thought the solvent might be evaporating and photoresist getting thicker).
We use fresh developer each time.
Can it be a rehydration problem or that the solvent is evaporating because our bottle is only 1/4 full?
The room humidity is fairly stable.

Thank you for your help

V.Soares
_________________
Virginia Soares
INESC-MN
R.Alves Redol,9
1000-029 LISBOA
PORTUGAL

[Guest]

Hello,

one possible reason for a poor development rate might be a contamination of the AZ 400K with metal-ion-free developers such as the AZ 326, 726 or 826 MIF. Even very small traces (ppm!) of the TMAH from these developers are known to strongly deteriorate the AZ 400K development rate.

May I additional ask what's the air humidity in your clean-room?

The temperatur of teh developer also strongly impacts on the development rate, a few ?C may cause several 10 % development rate.

Has the substrate changed? If - because of a different material or texture - the reflectiviy changed, this also causes a change in the effective exposure dose the resist 'sees' during exposure.

Kind regards!