Mapping of leakage and breakdown of dielectric films on silicon

Traditional evaluation of the electrical integrity of Si/SiO₂ systems relies on electrical tests performed using MOS capacitor structures that enable application of high electric fields across the oxide. The methodology presented here uses corona discharge as a means of application of the electric field over the entire surface of the wafer and a contact potential difference probe to measure the resulting charge and the oxide field/voltage. The maximum corona charge is limited by Fowler-Nordheim tunneling of electrons from the Si to the SiO₂ conduction band. For lower fields, i.e. in the sub-tunneling region, the oxide leakage is measured by monitoring a decrease of the oxide voltage with time at elevated temperature. The procedure is non-contact, non-destructive and produces full wafer maps in minutes.