Patent ID: 7910292

Claim:
A lithographic process for producing a microstructure from an SU-8 photoresist, wherein the SU-8 photoresist has a thickness in a range of 1.0 mm to 1.5 mm, comprising the steps of: (i) exposing a prebaked SU-8 photoresist on a substrate to light at a total energy density in a range of 18,000 to 35,000 mJ/cm 2 , wherein the light comprises a combination of wavelengths including g-line (436 nm), h-line (405 nm), and i-line (365 nm), and wherein the exposing further comprises: (a) exposing the SU-8 photoresist to the light without a filter; (b) exposing the SU-8 photoresist to the light with a first filter that filters out 80% of the light at 365 nm; (c) exposing the SU-8 photoresist to the light with a second filter that filters out 90% of the light at 365 nm; and (d) exposing the SU-8 photoresist to the light with a third filter that filters out all of the light at 365 nm; (ii) post-baking the SU-8 photoresist at a temperature of at least 60° C.; and (iii) developing the SU-8 photoresist in a solvent, whereby the microstructure is produced.