Electrical breakdown voltage in micro- and submicrometer contact gaps (100nm - 10?m) 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.