Extension of Two-Port Sneak Current Cancellation Scheme to 3-D Vertical RRAM Crossbar Array

3-D integrations are unavoidable task for new emerging memories, including resistive switching random access memory (RRAM), in order to overcome the market leading nand flash. However, an RRAM crossbar array (CBA) suffers severe read margin degradation due to the sneak current, which becomes even more critical as the memory density increases with the 3-D integration. In this paper, we extend the two-port readout scheme for a 2-D CBA, proposed in our previous work, to the 3-D vertical structure. A closed-form expression of the operating principle is derived, and HSPICE simulation using a 32 × 32 × 8 vertical RRAM CBA considering practical circuit parameters verifies feasibility of the two-port scheme to the 3-D CBA.