A field-enhanced Si–Si bond-breakage mechanism is presented which accurately describes the time-dependent dielectric breakdown behavior recently reported for thin-filmSiO2dielectrics over a wide range of fields and temperatures. The breakdown kinetics (both the field and temperature dependence) are shown to be consistent with a field-dependent dipolar energy term associated with an oxygen vacancy which serves to reduce the activation energy required for Si–Si bond breakage. ©1997 American Institute of Physics.