Depending on how one measures the dielectric breakdown strength of thermally grown films in the thickness range useful for MOSFET applications, different results may be obtained. These results are shown not to be an intrinsic property of the but rather are artifacts dependent on metallurgical contact thickness, oxide thickness, capacitor area, applied bias voltage, instrument impedance, and time constant. These parameters lead to phenomena commonly referred to as self‐healing (or nonshorting) breakdowns which represent a voltage collapse followed by thermal processes that vaporize the shorting electrode metal allowing the capacitor to break down repeatedly at higher fields. Statistical distributions of breakdown fields for the initial breakdown event point to a continuum of oxide defects having different breakdown fields in contrast to prior work showing specific defect types. Measurements of the final shorting voltage (after self‐healing breakdown events no longer occurred) are useful in determining the maximum dielectric strength of a defect‐free film. A ramp‐rate dependence of the breakdown field is observed for slow ramps, and a time instability is seen in the high‐field conduction which leads to breakdown.