Influence of Electrode Surface State on Air Gap Breakdown Characteristics at the Micrometer Scale

To investigate the influence of electrode surface roughness on gas discharge characteristics under micro-gap conditions, direct-current breakdown experiments were carried out in atmospheric air using a nano-positioning system. Breakdown tests were conducted for five metal electrodes over the electrode gap distances from 1 to 10 µm, and for one metal with different surface roughness levels over the electrode gap distances from 1 to 20 µm. Meanwhile, the electric field intensity distribution of aluminum electrodes (cathode) with different surface roughness values was simulated using Maxwell electromagnetic field simulation software. The experimental results show that, in the electrode gap distances from 1 to 5 µm, different metal electrodes exhibit different degrees of deviation from the Paschen curve, all of which are related to the work function. At the same electrode gap distance, the rougher the electrode surface, the larger the field enhancement factor β and the lower the breakdown voltage. Analysis indicates that surface protrusions cause local electric field intensification, allowing the field strength to reach the critical condition for field electron emission, thereby reducing the breakdown voltage. In the electrode gap distances from 10 to 20 µm, electrode surface roughness leads to a multiplication of the effective electron emission from the cathode surface, thus enhancing the surface electron emission process. Therefore, in the design of microelectronic devices, reducing electrode surface roughness and selecting metal electrode materials with higher work functions can effectively improve gas breakdown characteristics under small-gap conditions and optimize the insulation protection of microelectronic devices.