A Unified Framework to Explain Random Telegraph Noise Complexity in MOSFETs and RRAMs

Abstract

As well known, the implementation of $\text{high}-\kappa$ dielectrics (e.g., $\text{HfO}_{2})$ in nanoscale devices is unavoidable to cope with the device scaling required by the market. Nevertheless, due to the higher defect density compared to $\text{SiO}_{2}$, hafnium oxide exhibits stronger and more complex Random Telegraph Noise (RTN), namely one of the most relevant defect-related reliability issues in ultra-thin oxides. However, depending on the device type, $\text{HfO}_{2}$ can be characterized by different defect density and therefore leading to a different RTN signals. In particular, in Resistive Random Access Memory (RRAM) devices RTN arises very often but shows a high degree of complexity (e.g., multilevel, anomalous, temporary RTN) and instabilities [3], [4] which hinders its characterization. Conversely, in MOSFETs RTN has a small occurrence and it typically exhibits a simple behavior (i.e., 2-level signal) if detected. In this work, we fully analyze such phenomena in different devices providing a unified and physics-based framework which is also confirmed by experiments. The results of this study will be crucial for the design of new devices and circuits for emerging RTN-based applications, such as True Random Number Generators (TRNGs).