Comparison between high-field piezoresistance coefficients of Si metal-oxide-semiconductor field-effect transistors and bulk Si under uniaxial and biaxial stress

摘要

A comprehensive set of two-dimensional (2D) inversion layer piezoresistance coefficients (π-coefficients) was measured using four-point and concentric-ring wafer bending setups on the (001) and (110) surface, 〈110〉 and 〈100〉 channel, n- and ρ-type silicon (Si) metal-oxide-semiconductor field-effect transistors (MOSFETs). The extracted π-coefficients, including in-plane longitudinal, transverse, and biaxial π-coefficients, are compared to the published surface piezoresistance coefficients as well as the corresponding bulk Si values. For the (001)-oriented n-MOSFETs, the uniaxial π-coefficients depend on the applied electric field, doping density, and channel direction, while the biaxial π-coefficient has a relatively little electric field dependence. For the (001)-oriented ρ-MOSFETs, only the 〈110〉 transverse π-coefficient exhibits a strong dependence on the applied electric field. All π-coefficients for the (110)-oriented MOSFETs differ significantly from bulk Si values. A qualitative argument for the reported differences due to quantum confinement is given by investigating the 2D quantization effect.