Hi
i dont feel any regular photoresist will work for this much long time in HNA.
There is one posibility. If you want a resist to withstand for this
much long duration then we can go for Su8. Which is best negative
resist and can withstand for harsh etchant.
But before going for this, you should think about SU8 removal, which
is also bit difficult.

with regard.
abhay joshi,
Reserch Scholar,
Dept of Electronic Science,
University of Pune.