SEM voltage contrast mechanism of passivated devices

The mechanism of voltage contrast of passivated devices is investigated. Previous works on the voltage contrast over the passivation are reviewed, and experimental results on glass cover slips with a carbon‐coated surface are described. The voltage contrast is observed over the carbon‐coated equipotential surface. This result cannot be explained by the surface potential model of voltage contrast. An interpretation of the result using a contrast model previously introduced by the authors is provided.