A new model for dielectric-breakdown phenomenon in silicon dioxide films

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Abstract
A new model is proposed to interpret the breakdown phenomenon of dielectric thin films such as SiO2 films over the whole range of an applied field. It is suggested that two main mechanisms are responsible for the dielectric breakdown which is influenced by the geomorphic and physical parameters, and the examination conditions. One of the mechanisms is the avalanche breakdown, the so-called intrinsic type, which is caused by impact ionization. The other, the extrinsic type, is the filament-heating transport which induces a destructive breakdown. A simple mathematical model invoking the role of photon absorption is constructed to describe the effects of the band gap and the insulator thickness on the dielectric breakdown. It can be deduced from the model that (i) the mean distance of impact ionization is equivalent to the minimum thickness of the film generating the impact ionization and (ii) the probability of impact ionization is a function of the width of the band gap of the insulator under an applied field. Finally, effects of various processing conditions on the breakdown mechanisms and the dielectric strength are discussed.

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