Dual-Source-Line-Bias Scheme to Improve the Read Margin and Sensing Accuracy of STTRAM in Sub-90-nm Nodes

This brief analyzes the circuit-induced challenges to reliability and write current scaling of spin-torque-transfer random access memory (STTRAM). We show that, at sub-90-nm nodes, increased transistor leakage increases the probability of incorrect sensing requiring a higher read current. However, a higher read current can increase the read disturb failure, particularly with a reduced write current. To satisfy the conflicting requirements of read margin and sensing accuracy, we propose a source-line biasing technique. Simulations in predictive 65-nm nodes show that the proposed solution simultaneously reduce the sensing errors and improve the read margin.