Spatial Reliability Mapping of 16 nm FinFET FPGAs Using Distributed Ring-Oscillator Sensors

Advanced FinFET technologies exhibit pronounced within-die process variations and localized aging phenomena that challenge the accuracy of conventional global reliability monitoring. Existing Ring Oscillator (RO)-based aging monitors typically provide a single degradation indicator for the entire die, potentially masking vulnerable regions that experience accelerated wear-out. This work presents a spatial reliability monitoring methodology implemented on a commercial 16 nm FinFET FPGA. An array of 240 distributed ROs was organized into twelve physically separated monitoring regions to enable localized degradation analysis. We performed five independent accelerated aging experiments. Each experiment lasted 220 h under elevated electrical and thermal stresses while RO frequencies were sampled once per minute. The measured frequency degradation was translated into localized Time-to-Failure distributions using Weibull statistical analysis. The experimental results reveal significant spatial variations in both the Weibull shape parameter and accelerated-stress Time-to-Failure, demonstrating a correlation between regional process variation and localized degradation behavior. These findings show that global degradation metrics can obscure the earliest failing regions within the die. By transforming distributed frequency measurements into a spatial reliability health map, the proposed methodology provides an experimental framework for identifying vulnerable logic regions and supports future reliability-aware resource management and predictive maintenance in advanced FPGA platforms.