SiC nanowire-based SU-8 with enhanced mechanical properties for MEMS structural layer design

In addition to being used for pattern transfer, the negative photoresist SU-8 is widely used as a structural material in microelectromechanical systems (MEMS). Due to its good photopatternability, SU-8 has lower manufacturing costs than many other materials, but its mechanical properties are relatively weak to some extent, which limits its performance. The mechanical properties of epoxy-like SU-8 can be enhanced by adding micro- or nano-fillers such as carbon nanotube, clay, and SiC nanowire, which have superior elastic modulus. In this study, SiC nanowires were used to improve the mechanical properties of SU-8 while the SU-8 retains its photopatternability. The SiC nanowires were uniformly dispersed in SU-8 by stirring and ultrasonication. SU-8 materials with different SiC nanowire contents were fabricated into dog bone samples by lithography. The elastic modulus, storage modulus, and damping factor of the samples were measured by the Dynamic mechanical analysis (DMA) Q800. The experiment result shows that the rigidity and toughness increased, and the damping reduced. The 2 wt% SiC nanowires-reinforced SU-8 had a 73.88% increase in elastic modulus and a 103.4% increase in elongation at break. Furthermore, a spring component made by SiC-doped SU-8 could withstand greater acceleration. The SiC nanowires-reinforced SU-8 has the potential to meet higher requirements in the design and manufacture of MEMS and greatly reduce the manufacturing costs of MEMS devices.