Post Hard Breakdown Conduction in MOS Capacitors With Silicon and Aluminum Oxide as Dielectric

I-V curves as a function of voltage and temperature of MOS capacitors with silicon oxide and aluminum oxide after dielectric breakdown are presented. A different temperature behavior in accumulation is observed. The samples with aluminum oxide show an entirely positive temperature dependence, whereas the samples with silicon oxide have a crossover of the temperature dependent curves. This difference of the two sample types is attributed to the charge distribution according to the material of the breakdown spot, silicon for the case of silicon oxide, and aluminum for aluminum oxide. Thus, in the first case, a p-n junction is formed while a Schottky contact is created in the latter case. Atlas simulations and TEM analysis are presented that confirm this hypothesis.