Physical-Based Threshold Voltage and Mobility Models Including Shallow Trench Isolation Stress Effect on nMOSFETs

Abstract

Physical-based threshold voltage and channel mobility models to include shallow trench isolation (STI) mechanical stress effects on MOSFET I-V characteristics were described. The parameter Δs, meaning the change along the MOSFET channel length under STI stress, ΔEeceg , ΔEdos, and ΔEm, meaning the activation energy per strain due to STI stress are used in models. ΔEeceg describes the STI-stress-induced electron affinity, band-gap narrowing effects. ΔEdos describes density-of-states changes due to the light and heavy hole mass changes under STI stress, and ΔEm corresponds to the STI-stress-induced mobility changes. The STI stress induced tens of millivolts shifts in threshold voltage, and 40% shift in channel mobility on nano-MOSFET region. The models are verified by the 130-nm technology nMOSFET-layout-dependent experiment data including various gate length, active area, and gate location.