Atomic Defects Profiling and Reliability of Amorphous Al2O3 Metal–Insulator–Metal Stacks

We present a comprehensive characterization of amorphous alumina (a-Al₂O₃) high- ${k}$ dielectric in metal–insulator–metal (MIM) stacks, self-consistently extracting the space-energy distribution of a-Al₂O₃ atomic defects and the related bond-breaking process parameters. Active defects are profiled via simultaneous simulation of current–voltage ( ${I}$ – $\textit {V}$ ), capacitance–voltage (CV), conductance–voltage (GV) (i.e., defect spectroscopy), and low-field ${I}$ – ${V}$ hysteresis analysis. The defect energies extracted ( ${E}_{TH}= 1.55$ and 3.55 eV) are consistent with oxygen vacancies and aluminum interstitials. The voltage-dependent dielectric breakdown (VDDB) statistics of a-Al₂O₃ is investigated using ramped voltage stress (RVS). The VDDB statistics show a complex and polarity-dependent breakdown statistics, correlating with defect distributions, which allows estimating the a-Al₂O₃ bond-breaking parameters with the support of multiscale atomistic simulations of the breakdown process.

I. Introduction

The development of novel, emerging electron devices increasingly requires the adoption and combination of high dielectric constant (high-) dielectrics [1], [2]. Among them, amorphous aluminum oxide (a-Al₂O₃) is a particularly interesting material, combining a high dielectric constant, a relatively large band gap, large band offsets with respect to silicon, high breakdown field, ease of fabrication with a low thermal budget, high uniformity, and excellent stability [3].