(348g) Tribological Impact of Surface Texturing Using Gold Nanoparticles On MEMS

Since the advent of Micro-electromechanical systems (MEMS) technology, researchers have used surface texturing as one of the approaches to alleviate unintentional adhesion in MEMS. The conventional methods used for surface texturing are reported to reduce in-plane adhesion by a factor of 20 and the recently devised surface texturing method, which involves the deposition of gold nanoparticles using a gas-expanded liquid technique, is reported to reduce it by two orders of magnitude. Since the effect of gold nanoparticle based surface texturing was investigated using inherently rough polysilicon test surfaces, we suspect that it was subdued by the inherent roughness of the test surfaces. Also, there is a need to investigate the effect of gold nanoparticle based surface texturing on other tribological properties of contacting surfaces. Therefore, we report on an investigation of the effects of gold nanoparticle based surface texturing on several tribological properties of MEMS surfaces, conducted using relatively smoother test surfaces. The tribological properties investigated include in-plane stiction, sidewall stiction as well as static friction. The test surfaces are textured by depositing dodecanethiol capped gold nanoparticles from CO2-expanded hexane. The dodecanethiol capping ligands are removed by exposing the textured surfaces to UV-Ozone atmosphere for an hour, after which the textured surfaces are characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The textured surfaces exhibit significantly reduced stiction as well as friction as compared to untextured surfaces having only native oxide on them.