Experimental study of electrical breakdown in MEMS devices with micrometer scale gaps

Abstract

We present an experimental study of the DC breakdown voltage of MEMS interdigitated aluminum electrodes with gaps ranging from 10 to 500 µm. Unlike most research on MEMS electrodes that was done at atmospheric pressure, our work has focused on the effect of gas pressure and gas type on the breakdown voltage. A main goal was to identify geometries that favor the creation of low-voltage discharges. Helium, argon and nitrogen pressure was varied from 10 2 to 8.10 4 Pa (1 to 800 mbar). The breakdown voltage was plotted as a function of the Paschen reduced variable P red = p·d. For higher values of pressure, p or gap, d (high P red ), classical Paschen scaling was observed. For lower values of P red however, significant deviations were seen, particularly at low pressures. We attribute these differences not to field emission, but to the scale of the mean free path (which explains the higher than predicted voltages), and principally to the many length scales effectively present in our planar geometry (on-chip and even off-chip, that lead to the superposition of several Paschen curves). Guidelines are proposed for low-pressure operation of MEMS to avoid or to encourage breakdown.

Characterization of Electrical Breakdown for Low and High Pressure Hydrogen Gas in Coaxial Virtual Cathode Device

“…[34] For most gases, the minimum breakdown voltage is between 100 and 500 volt and occurs for Pd in the range of 10 −1 ‫ـ‬ 10 torr•cm [35]. The minimum breakdown voltage for noble gas increases with the increase of the work function of the cathode material and high secondary electron emission [32].…”

Micromachined chip-scale plasma light source

“…This data comparing different gases was taken on electrodes with a 20 m gap. Reference [15] presents a study of the effect of gap size and pressure on breakdown voltage. Fig.…”

“…At larger gaps deviations are also reported, in particular for RF operation because of the additional length scales brought into play for RF operation [17]. A study of DC breakdown voltage for different electrode configurations to measure the Paschen curve at reduced pressures for gaps from 10 to 500 m is reported in [15].…”

Thrust and Efficiency Performance of the Microcavity Discharge Thruster

“…In brief, for MCD devices intended for illumination, in which the cavity does not pass all the way through the electrode, the dominant electrode separation distance is in fact the diameter of the microcavity. (Park, et al, 2002) However, in the case of the MCD thruster using the cavity diameter as the electrode separation distance resulted in values that differed greatly from the DC breakdown curves given in Carazzettia et al (Carazzettia, 2009) Once the characteristic was modified to use the separation distance between the parallel foils the Paschen breakdown results fell in agreement with DC breakdown values, as shown in Figure 7.3 and described in de Chadenedes et al (de Chadenedes, et al, 2010) When the cavity diameter is used in the characteristic, there is a stark contrast in the Paschen minimum between the MCD thruster and DC devices, illustrated in Figure 7.3. This result leads to the conclusion that for non-static MCD devices, the appropriate separation distance is the gap between the two parallel aluminum substrates.…”