Piezoresistance coefficients of (100) silicon nMOSFETs measured at low and high (similar to 1.5 GPa) channel stress

A flexure-based four-point mechanical wafer bending setup is used to apply large uniaxial tensile stress (up to 1.2 GPa) on industrial nMOSFETs with 0 to similar to 700 MPa of process-induced stress. This provides the highest uniaxial channel stress to date at similar to 1.5 GPa. The stress altered drain-current is measured for long and short (50-140 nm) devices and the extracted pi-coefficients are observed to be approximately constant for stresses up to similar to 1.5 GPa. For short devices, this trend is seen only after correcting for the significant degradation in the pi-coefficients observed due to parasitic source/drain series resistances (R-s/d).