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.