Testing, diagnosis and repair methods for NBTI-induced SRAM faults

Abstract

NBTI is a major SRAM aging mechanism, leading to reduced read and hold static noise margins, and increased soft error rate. The existing techniques including guard banding, on-chip sensor-based detection, and recovery. In this paper, we propose a group of testing, diagnosis, and repair methods for NBTI-induced memory faults. We observe that NBTI leads to SRAM read errors rather than write errors. We propose to identify NBTI-induced memory read errors based on the existing ECC circuitry, differentiate them with soft errors by correction and double checking, and keep them idle for recovery. We further propose an predictive test method for NBTI-induced memory faults by adaptive body biasing. We achieve an adaptive body biasing formula to simulate the NBTI effect. Our experimental results validate the proposed methods and show that they cost little silicon area and power consumption.