Electrical Breakdown in Thin Si Oxide Modeled by a Quantum Point Contact Network

The voltage and temperature dependence of post-breakdown (BD) conduction in SiO
₂
non-volatile memory bitcells is investigated. A model for charge transport in disordered systems is adapted to describe conduction through the BD path. The model uses a 2-D network of the quantum point contacts (QPCs) to simulate the oxide, and successfully reproduces the characteristics of experimental post-BD current in a large set of devices. Importantly, the temperature dependence in this model arises from the Fermi function rather than the structural changes in the oxide as suggested by previous studies. Once the QPC network model is fit to the experimental current-voltage (I-V) characteristics at one temperature, it is shown to correctly predict the I-V behavior at other temperatures without any additional parameters. Experimental I-V data from 100 devices that experience progressive BD are fit using the QPC network model, and for comparison, also using a single QPC model. We conclude that a QPC network gives a more realistic description of post-BD conduction than the single QPC model, as the network includes multiple path conduction and correctly describes the temperature dependence.