Making thick photoresist SU-8 flat on small substrates

This work suggests a simple method to flatten thick layers (∼50–200 μm) of SU-8 photoresist on small substrates (∼1 cm). The method sidesteps the edge beads problem and enables photolithography patterns up to the substrates' edges. Moreover, the method can be used even for substrates with large aspect ratios when the spin coating is largely impossible. (technical note)