Characterizing the Channel Backscattering Behavior in Nanoscale Strained Complementary Metal Oxide Semiconductor Field-Effect Transistors

Abstract

This work investigates the impact of different uniaxial strain polarities on channel backscattering in nanoscale complementary metal oxide semiconductor field-effect transistor (CMOSFET). Two carrier statistics, nondegenerate and degenerate-limited, are employed to extract the channel backscattering ratio, ballistic efficiency, and related backscattering factors. While the channel length scales down and the channel stress level increases further, the modulation of channel backscattering ratio, i.e., improved (degraded) by uniaxial tensile (compressive) strain, becomes more prominent. This observation holds true under both carrier statistics, which implies that the nondegenerate case with simple mathematics can be fairly used for evaluation. In addition, the correlation between strain-enhanced mobility gain and drain current improvement is found to be predicted well by the ballistic efficiency deduced with the nondegenerate carrier statistics.