I would actually be more likely to look at my exposure to begin with.

There is a wide variety of photolithographic materials out there, ranging from
ultra-thin (<100nm) to ultra-thick (>100 μm), and the process parameters will
depend on which material you are using.

Which photoresist are you processing with, to what thickness, and what is your
exposure process (dose, lamp intensity).

Best Regards,
Chad Brubaker