Time dependent breakdown in silicon dioxide films†

Abstract

Thermally grown silicon dioxide films on silicon were examined for time dependent, breakdown. Measurements were performed on MOS capacitors with 1100 A oxide thickness with positive voltage on the metal. A time dependent breakdown mechanism was found, which could be described as a time to breakdown, τBD and a maximum breakdown probability, reached at. times much larger than τBD. It was furthermore found that τBD could be written τBD~exp (Qo — ∞ √E)/kT and that 25 V appeared to be a lower limit of the breakdown voltage. A possible explanation is proposed. Sodium tons are assumed to drift to the silicon surface, piling up at that surface, thus lowering the barrier for Fowler-Nordheim electron injection.