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In-vacuum surface flashover of SiN, AlN, and etched SiO2 thin films at micrometre scales

Vijay Kumar, Martin Siegele-Brown, Matthew Aylett, Sebastian Weidt, Winfried Karl Hensinger

Abstract

We investigate the surface flashover voltage threshold for SiO$_2$, SiN, and AlN thin films over micrometre scale lengths. Furthermore, we test the effects of different etching chemistries on SiO$_2$ layers. We find that there is little significant difference between untreated SiO$_2$ samples and those that have been etched with hydrogen fluoride or Transene AlPad Etch 639. SiN and AlN samples performed significantly better than all SiO$_2$ samples giving a 45% increase in surface flashover voltage at a distance of 5 $μ$m with the difference increasing with electrode spacing.

In-vacuum surface flashover of SiN, AlN, and etched SiO2 thin films at micrometre scales

Abstract

We investigate the surface flashover voltage threshold for SiO, SiN, and AlN thin films over micrometre scale lengths. Furthermore, we test the effects of different etching chemistries on SiO layers. We find that there is little significant difference between untreated SiO samples and those that have been etched with hydrogen fluoride or Transene AlPad Etch 639. SiN and AlN samples performed significantly better than all SiO samples giving a 45% increase in surface flashover voltage at a distance of 5 m with the difference increasing with electrode spacing.

Paper Structure

This paper contains 4 sections, 2 equations, 4 figures, 1 table.

Table of Contents

  1. Data availability statement
  2. Acknowledgments
  3. References
  4. Supplementary information

Figures (4)

  • Figure 1: Sample damage after surface flashover. Damage is seen on the corners of the electrodes where the electric field is concentrated.
  • Figure 2: Electrode structure of surface flashover test chips. The distances to flashover are 5, 15, 25, 50, 75, and 100µm.
  • Figure 3: Raw IV data collected from a sample under test. The voltage is increased until surface flashover is detected by a spike in measured current. Surface flashover occurs above approximately 1.5kV.
  • Figure 4: Surface flashover as function of electrode separation for different dielectrics (SiO$_2$, SiN, AlN) response from samples. The measurement data is fitted to equation \ref{['distance']} using a non-linear least squares regression method. The units of $\tau$ are in V/m$^2$. Data for AlN above 100$\mu$m was not recorded as the applied voltage caused breakdown of the mounting PCB before breakdown of the device under test.