An Alternate Design Paradigm for Robust Spin-torque Transfer Magnetic RAM (STT MRAM) from Circuit/Architecture Perspective

Abstract

Spin-Torque Transfer Magnetic RAM (STT MRAM) is a promising candidate for future embedded applications. It provides desirable memory attributes such as fast access time, low cost, high density and non-volatility. However, variations in process parameters can lead to a large number of cells to fail, severely affecting the yield of the memory array. In this paper, we provide a thorough analysis of the impact of design parameters on parametric failures due to process variations. To achieve high memory yield without incurring expensive technology modification, we developed an alternate design paradigm —circuit/architecture co-design — to take advantage of different levels of design hierarchy (circuit and architecture) to improve the yield and memory density. The technique decouples the conflicting design requirements for read stability/writability and density. Consequently, the memory cell failure probability reduces by 48% and cell area reduces by 21% with negligible performance degradation (~0.4%).