Laser processes for MEMS manufacture

This paper discusses the use of excimer lasers in the manufacture of microelectromechanical devices and systems, with emphasis on two application areas: laser micromachining of polymer masters for replication in metal by electroplating (Laser-LIGA), and laser-assisted manipulation of microparts for hybrid assembly. As a master fabrication method, laser micromachining offers advantages over conventional UV lithography in terms of materials flexibility and 3-dimensional capability. However, these advantages are offset by higher cost and lower throughput. We have been using a combination of laser micromachining and UV lithography to produce relatively complex multi-level fluidic devices, with laser micromachining being used only for layers requiring greater structural height and/or 3D profiling. Process details and examples of prototype devices are presented. Laser-assisted assembly is a new technique based on release and transport of parts by ablation of a sacrificial layer, using light incident through the substrate. We have been using this approach to assemble microelectromechanical devices from parts fabricated on separate substrates. Fundamental aspects of the process are discussed, and results are presented for hybrid electrostatic micromotors assembled by laser-assisted transfer of nickel parts.