Multiple Digital Breakdowns and Its Consequence on Ultrathin Gate Dielectrics Reliability Prediction

1/f-like noise measurements of gate leakage current (Ig) at the different stages of progressive breakdown (BD) confirm that a percolation path in ultrathin gate dielectrics could grow from an unstable physical structure in digital BD into a stable physical structure in analog BD. A model involving E´-centers and neutral oxygen vacancies is developed to explain the digital fluctuation and the digital-to-analog transformation of I_g. The model suggests that at low voltages, multiple percolation paths are more likely to occur in a device with digital BD, affecting the post-BD lifetime of a device operating at nominal voltages.