Improved process for high yield 3D inclined SU-8 structures on soda lime substrate towards applications in optogenetic studies

We report an improved process for backside inclined lithography. The specific improvement is the combination of backside inclined exposure and glycerol medium index matching with a Parylene adhesion layer. This method allows for high aspect ratio SU-8 inclined structures with large surface contact areas on soda lime substrates for optical applications in optogenetic studies. Improved yields over the entire wafer were achieved with improved SU-8 substrate adhesion and perfect gapless contact between the masked substrate and SU-8. The surface roughness of the SU-8 structures is less than 8 nanometers, smooth enough for use as mirrors.