Analytical model for TDDB-based performance degradation in combinational logic

With aggressive gate oxide scaling, latent defects in the gate oxide manifest as traps that, in time, lead to gate oxide breakdown. Progressive gate oxide breakdown, also referred to as time-dependent dielectric breakdown (TDDB), is emerging as one of the most important sources of performance degradation in nanoscale CMOS devices. This paper describes an accurate analytical model to predict the delay of combinational logic gates subject to TDDB. The analytical model can be seamlessly integrated into a static timing analysis tool to analyze TDDB effects in large combinational logic circuits across a range of supply voltages and severity of oxide breakdown. Simulation results for an early version of an industrial 32 nm library show that the model is accurate to within 3% of SPICE with orders of magnitude improvement in runtime.