Mechanical Characterization of KMPR by Nano‐Indentation for MEMS Applications

The ability to create high-aspect ratio structures (HARS) are extremely important for many MEMS sensors and actuators applications such as gyros, accelerometers, and pumps. Traditionally, HARS are fabricated using LIGA [1] and ICP techniques. However, the expensive and the consuming LIGA process is usually unaffordable and the silicon ICP process usually suffers from poor sidewall quality. As a result, the UV based LIGA-Like process becomes a competitive fabrication process for creating HARS in polymeric materials. During the past decade, with the negative photosensitive resin, SU-8, UV LIGA-Like process has successfully demonstrated its capability in shaping HARS. However, SU-8 needs stringent temperature and time control in baking cycle to avoid cracking and potentially, the reliability of the fabricated structure become a concern. Recently, a new negative photosensitive resin, called KMPR™ [2], has been reported to have better characteristics in fabrication and it does not require tight baking control. It has the potential to replace SU-8 in the future. However, to our best knowledge, its mechanical properties are not yet reported and this represents a gap for related MEMS design. The purpose of this paper is therefore to provide specific material properties, namely hardness and elastic modulus of KMPR after different thermal treatments via nano-indentation [3] for MEMS design.