Cost efficient master fabrication process on copper substrates

In this work a rapid and low cost process for master fabrication was carried out. Thick epoxy SU-8 photoresist was employed as sacrificial patternable layer for the definition of metal deposition area. An SU-8 photolithographic recipe was employed on low cost copper substrates, without the use of a seed layer. In particular an improvement of SU-8 adhesion, for structures with 7:1 aspect ratio, was obtained. This process was characterized by Field Emission Scanning Electron Microscope analysis on metallic substrates and it was compared with other UV-LIthographie Galvanoformung Abformung processes. An electrolytic Cu deposition was used to fabricate the master and, since the metal was deposited directly onto the copper substrate, the simplified LIGA-like process did not require silicon substrate removal or mechanical polishing. Hence, the fabrication steps and process time were considerably decreased. Finally, different molds with microfluidic patterns for hot embossing replication were obtained in 24 h with a significant costs reduction.