Detection of inhibitory effects in the generation of breakdown spots in HfO_2- based MIM devices

摘要

In this work, the connection between the generation of catastrophic breakdown (BD) spots in metal-insulator metal capacitors with a high-permittivity dielectric film (HfO2) and their spatial distribution was investigated. To gain insight into this issue, large area devices (10(4) mu m(2)) were constant voltage stressed at high electric fields (3.5 MV/cm) with the aim of generating a large number of spots in a single device. The set of BD spots was analysed as a point pattern with attributes (their sizes) using the methods of spatial statistics. Our study reveals that beyond the visible damage on the top metal electrode, the spots exhibit soft inhibitory regions around them where the creation of new spots is less likely. The origin of these inhibitory regions is ascribed to structural modifications of the dielectric layer in the vicinity of the spots caused by the huge thermal effects occurring at the very moment of the BD event.