PCRAM And RRAM Memories

This research work on non-volatile resistive memories includes: oxide-based memories in MIM (Metal-Insulator-Metal) structure such as OxRAM and CBRAM (Conductive Bridge RAM), but also PCM (Phase Change Materials) .

For these different dissertations, this work was mainly done in collaboration with the CEA-LETI and the STMicroelectronics company (mainly via CIFRE theses and two European projects).

For resistive memories in MIM structure we mainly focused on the HfO2 oxide and the understanding of the switching mechanisms depending on the nature of the electrodes.

We then showed that for certain electrodes we could obtain hybrid memories, mixed OxRAM/CBRAM, namely that the presence of oxygen vacancies in the oxide favors the diffusion of the metal ion. We also succeeded in switching the capacitance of the MIM structure from positive to negative values in a reversible and non-volatile manner, thus defining a new component allowing a variation of impedance and not only of resistance as illustrated in the figures below which show write and erase cycles for the capacitance and conductance of an optimized MIM structure (for more information see the publication by T. WAKRIM et al, Appl. Phys. Lett. 108, 053502 (2016) ).

In the case of PCM memories, we were mainly interested in their development using an original plasma-assisted CVD process as well as their characterization in order to study the impact of aging of these memories on their performance properties phase change.