A novel physics-based variable NBTI simulation framework from small area devices to 6T-SRAM

A novel simulation framework is developed to study NBTI variability in devices and SRAM circuits. Stochastic Reaction Diffusion (RD) model for interface trap generation (ΔN
_IT
) and stochastic 2 well model for charging of pre-existing bulk traps (ΔN
_HT
) are interfaced with TCAD for electrostatics and time-zero variability to determine variable NBTI in device level. Distributions of ΔN
_IT
and ΔN
_HT
are generated for stress and recovery. ΔV
_T
and V
_T
distributions are generated using empirical exponential impact and full TCAD simulations. Simulated ΔV
_T
distributions match with experiments, analytic models and show correlation between mean and variance. Impact of NBTI variability on read, write and hold failure of 6T-SRAM is simulated by using SPICE. NBTI variability of these SRAM metrics is correlated to device V
_T
variability.