Electrical breakdown voltage in micro- and submicrometer contact gaps (100nm - 10µm) in air and nitrogen

In this paper, we present the results of electrical breakdown experiments performed in a contact gap ranging from 100nm to 10μm under air and nitrogen environment. The electrodes arrangement corresponds to a point-plane system and consists in a probe tip with a radius of curvature of 20μm and a perfectly flat electrode. A high precision piezoelectric actuator provides to the system a static resolution of ±30nm allowing to investigate submicrometer contact gaps. Numerous experiments have been performed at those distances (<;1μm), a range rarely explored in the literature so far. The results highlight the presence of a pre-disruptive current and the deviation to the Paschen's law. Two breakdown mechanisms can be identified. Above 4μm, the breakdown voltage values are in good agreement with the so called “Paschen's law” (electrical breakdown vs contact gap × pressure). From 1μm to 4μm, the value of the breakdown voltage corresponds to the Paschen's minimum. This plateau can be explained by the fact that the breakdown does not occur at the minimum distance but when the pressure/distance couple corresponds to the Paschen's curve minimum. Below 1μm, a completely different behavior is observed as the breakdown occurs according to a constant electric field of 350V/μm. Emission spectroscopy highlights the presence of a metal plasma that could explain such a breakdown in the micro-gap.