This paper focuses on hot carrier (HC) effects in large scale digital circuits and proposes a scalable method for analyzing circuit-level delay degradations. At the transistor level, a multi-mode energy-driven model for nanometer technologies is employed. At the logic cell level, a methodology that captures the aging of a device as a sum of device age gains per signal transition is described, and the age gain is characterized using SPICE simulation. At the circuit level, the cell-level characterizations are used in conjunction with probabilistic methods to perform fast degradation analysis. The proposed analysis method is validated by Monte Carlo simulation on various benchmark circuits, and is proved to be accurate, efficient and scalable.