Hopping and tunnelling trap assisted current in metallic oxide based non volatile memories

Despite the current hegemony of Flash technology for data storage, new memory component architectures have recently entered production. Thus, ST Microelectronics currently markets a microcontroller based on phase change memories (PCM), while Intel and Samsung currently produce components based on magnetic memories (SST-MRAM). In this context of diversification of architectures, OxRAM memory cells, based on the reversible breakdown of a layer of HfO2, are the subject of much research which has already demonstrated the excellent performance of these memories in terms of retention, endurance, programming window, size reduction, ease of fabrication, back-end compatibility, and programming time. Since these write and erase times can be less than a nanosecond, OxRAM non-volatile memories could also compete with certain applications as random access memories. However, a major obstacle is blocking their industrial development: it is their variability. Indeed, the characteristics of these components are not only highly variable between components, but also between each programming cycle. Moreover, the mechanisms governing their reliability are not understood, and recent results obtained by the CEA-LETI and the IMEP-LAHC tend to demonstrate a proximity between the statistical nature of their characteristics and their lifetimes.