Highly Efficient Extraction of Mechanical and Linear and Quadratic Piezoresistive Properties of Poly-Si Films using Wafer-Scale Microtensile Testing

This paper reports on the extension of the wafer-scale microtensile technique to the piezoresistive characterization of thin-films, demonstrated for in-situ n-doped poly-Si layers. In addition to the reliable extraction of mechanical properties, this extended high-throughput method enables the acquisition of linear and, for the first time, nonlinear piezoresistive coefficients, namely the first and second order longitudinal parameters, pi_l,1 and pi_l,2, respectively, with statistical significance. In contrast to previous studies, the data presented here are extracted for strains up to the fracture value, leading to meaningful linear and quadratic piezoresistive parameters. Along with the mechanical properties, these values are especially important for sensing applications where poly-Si films are subjected to significant levels of stress and strain.