Resistive Switching Comparison Between Cu/TaOx/Ru and Cu/TaOx/Pt Memory Cells

Building nonvolatile memory (NVM) directly into a CMOS low-k/Cu interconnect module would reduce latency in connectivity constrained devices and reduce chip's footprint by stacking memory on top of the logic circuits. One good candidate for NVM is the well behaved Cu/TaOx/Pt resistive switching device. However, since platinum (Pt) is not an economic choice for industrial production, a BEOL-compatible replacement of Pt is highly desirable. A good candidate to replace Pt is ruthenium (Ru) which has been already deployed in the CMOS BEOL. Cu/TaOx/Ru and Cu/TaOx/Pt devices were manufactured with the latter device used as a benchmark for the Ru device performance assessment. The electric characterization of both devices has shown many similarities and some notable differences. Compared with Cu/TaOx/Pt, Cu/TaOx/Ru device shows less reliable set and reset switching characteristics due to the different formation, shape and rupture of the conductive filament.