8-Layers 3D vertical RRAM with excellent scalability towards storage class memory applications

For the first time, we experimentally demonstrated a bit cost scalable (BiCS) 8-layer 3D vertical RRAM with ultimate scalability. The design of self-selective cell (SSC) with non-filamentary switching were successfully extended to 8 stacks and exhibits salient features, including high nonlinearity (>10
²
), forming free and high endurance (>10
⁷
). An extremely scaled 3D structure with 5 nm size and 4 nm vertical pitch was further demonstrated. The sub μA operation current is quite promising for low power applications, but not good for sensing speed. A fixed bitline voltage sensing circuit was proposed to address the latency issue. Sub-μs read latency in bit sensing mode was successfully achieved.