Accuracy Improvement of Multi-parameter Estimation in Combined Photocarrier Radiometry and Free Carrier Absorption for Characterization of Silicon Wafers

Abstract

Numerical simulations are performed to investigate the effect of experimental parameters on the simultaneous determination of the electronic transport properties (namely, the carrier lifetime, the carrier diffusion coefficient, and the surface recombination velocities) of semiconductor wafers in the combined photocarrier radiometry (PCR) and free carrier absorption (FCA) technique via a multi-parameter estimation procedure. The uncertainties of the fitted parameter values are analyzed by investigating the dependence of a mean square variance including both amplitude and phase errors on the corresponding transport parameters. Simulation results show that the optimal experimental conditions with a combination of an appropriate pump-probe-beam separation and a small (comparable to or slightly larger than the pump beam radius) detection radius in FCA, as well as a large (1 mm) detection radius in PCR, can noticeably reduce the uncertainties of the simultaneously fitted transport properties of wafers.