A Precise Negative Bias Temperature Instability Sensor using Slew-Rate Monitor Circuitry

Abstract

Negative Bias Temperature Instability (NBTI) has become an important cause of degradation in scaled PMOS devices, affecting power, performance, yield and reliability of circuits. This paper proposes a scheme to detect PMOS threshold voltage (V-TH) degradation using on-chip slew-rate monitor circuitry. The degradation in the PMOS threshold voltage is determined with high resolution by sensing the change in rise time in a stressed ring oscillator. Simulations in IBM\'s 65nm PD/SOI CMOS technology demonstrate good linearity and an output sensitivity of 0.25mV/mV using the proposed scheme.