Micro/nanomechanical characterization of ceramic films for microdevices

Abstract

Microelectromechanical systems (MEMS) are currently fabricated using single-crystal silicon, various polysilicon films and other ceramic materials. Silicon carbide (SiC) film has recently been pursued as a material for use in MEMS devices owing to its excellent mechanical properties and high-temperature capabilities. Since physical and chemical properties, friction and wear are important issues in such small-scale devices, it is essential that the materials used in MEMS have good micro/nanomechanical and tribological properties. Micro/nanomechanical characterization of single-crystal 3C-SiC (cubic or β-SiC) films, undoped and doped (n+-type) polysilicon films have been carried out. For comparison, measurements on undoped single-crystal Si(100) have also been made. Hardness, elastic modulus and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Fracture toughness was measured by microindentation using a microindenter. Friction and wear properties were measured using an accelerated ball-on-flat tribometer. It is found that the 3C-SiC film exhibits higher hardness, elastic modulus and scratch resistance as well as lower friction compared to other materials. These results show that the 3C-SiC film possesses desirable micro/nanomechanical properties that make it an ideal material for use in MEMS devices.