Hi!
re: 'mousebites"

I have worked extensively in Silicon Valley with various photoresists
and we have usually termed 'mousebites' to poor resist adhesion to metal
layers. However, I have seen it on various layers. It can be caused by
over- or under-Vapor Priming, incorrect prebake temperatures(softbake),
moisture as mentioned, and sometimes highly doped surfaces like
Phosphorus will cause it to peel. "Mousebites' are also seen after wet
metal etch, especially if lines are going over high steps (>1um).
If you're not using it on metal and you're seeing it, I would check
for moisture in lines somewhere or in process, and then check your bake
temp. Is the resist expired? Has it gelled? If it was ever stored
improperly, ie.>55 degrees, it ages quicker and can cause separation of
its constituents.
good l uck!
dh