UV laser beam lithography for ultra-deep epoxy-based structures

Soft lithography is widely used for fabricating microfluidic devices due to its cost-effective and straightforward replication process. Critical to this process is the precise development of a master. Maskless Laser Beam Lithography (LBL) is advantageous for creating polymeric masters and rapid prototyping complex devices, offering design freedom, integration of micro-optical/electrical elements, and cost-effectiveness. However, LBL can produce sub-optimal results with thick layers due to depth of focus limitations, affecting sidewall verticality. This work explores overcoming these limitations by testing SU-8 based negative resists at thicknesses over 0.3 mm, discussing sidewall verticality, aspect ratios up to 1:30, and spatial resolution limits. Potential applications and broader impacts of these micromachining capabilities are also examined.