Discharge behaviors of electrical breakdown across nanometer vacuum gaps

Micro-electro-mechanical systems (MEMS) and Nano-electro-mechanical systems (NEMS) are emerging technologies that uses tools and techniques in the microelectronics industry to build microscopic machines. Electrostatic force is often employed to drive the motion components in MEMS and NEMS devices, which could cause extremely high electric field (more than 10⁸ V/m) between two metal conductors. However, the high field intensity may result in electrical breakdown across the conductors in case of improper operations or overvoltage. Therefore, this paper presented a novel experimental technique to study the discharge behaviors across nanometer gaps between 20 nm and 300 nm. The influence of gap separations on breakdown characteristics and the voltage contrast effect in the gap spacing were both investigated. Results showed that the field electron emission did not play a dominate role in the electrical breakdown process across nanometer gaps, which was different from the classical theory of vacuum breakdown, and the breakdown voltage increased as the increase of gap separations. Besides, the voltage contrast effect in the gap spacing was also observed through the scanning electron microscope, which was related to the electric field intensity.