Self-Repairing SRAM Using On-Chip Detection and Compensation

Abstract

In nanometer scale static-RAM (SRAM) arrays, systematic inter-die and random within-die variations in process parameters can cause significant parametric failures, severely degrading parametric yield. In this paper, we investigate the interaction between the inter-die and intra-die <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V t</i> variations on SRAM read and write failures. To improve the robustness of the SRAM cell, we propose a closed-loop compensation scheme using on-chip monitors that directly sense the global read stability and writability of the cell. Simulations based on 45-nm partially depleted silicon-on-insulator technology demonstrate the viability and the effectiveness of the scheme in SRAM yield enhancement.