Bonding, exposing and transferring technique in SU-8 and SU-8 laser micromachining combination for 3D, free-standing and multilevel microstructures

This Letter reports a simple laser process to fabricate three-dimensional, free-standing and multilevel polymeric (SU-8) microstructures using a nanoseconds neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. The proposed process is intended to be a complement for the bonding, exposing and transferring technique in SU-8 (BETTS) process in MEMS applications. Thanks to this technique, BETTS-laser micromachining, the fabrication of free-standing 3D SU-8 microstructures can be performed, decreasing the number of steps of the typical SU-8 process. Furthermore, it improves the aspect ratio of BETTS-based planar microstructures, and also allows the fabrication of 3D microstructures which are not possible to fabricate using BETTS, or the typical SU-8 process. To prove the viability of BETTS-laser micromachining process, several microstructures have successfully been fabricated.