Demonstration of graphene contact MEMS switch and its characterization

Abstract

Over the last a few decades, microelectromechanical system (MEMS) technology has established itself as a 21st century key technology thanks to the maturity of bulk and surface micromachining process. Nevertheless, the reliability issue remains as a major bottleneck to the commercialization since most MEMS switches suffer from various failure mechanisms within few cyclic operations. For reliable operation, gold (Au) is commonly and typically used due to its resistive characteristics to chemical contamination, excellent electrical property, and so on. However, Au still has a failure problem due to its lack of mechanical properties and this event requires deeper understandings and more thorough investigations toward the contact material of MEMS switches. Therefore, more studies about MEMS contact material are needed. Recently, graphene has actively been researched and given remarkable attentions. The graphene has its own excellent mechanical, chemical, electrical, and thermal properties; therefore, it is expected to be a superb candidate for a MEMS switch contact material. However, the graphene contact MEMS switch has not been developed due to its difficulty of fabrication. In this thesis, we developed and demonstrated the novel fabrication method which uses the graphene as a contact material for the MEMS switch. The lateral type switch was suggested as the graphene to graphene contact device without any fabrication problems. After demonstration, the characterization of the graphene contact switch was performed to confirm the graphene could be an alternative material for the MEMS switch contact. The material properties were compared with Au-typical contact material in MEMS switches. Two directional characterizations were performed which dealt with critical issues in MEMS switch contact field; physical surface change and adhesion force change. Atomic force microscopy (AFM) force-distance (F-D) method and I-V curve analyz-ing were used to investigate the physical ...