Nonlinear fundamental photothermal response: experimental results for tungsten

A quantitative analysis based on a new three-dimensional nonlinear theoretical model of the experimental fundamental nonlinear photothermal response from multilayer structures containing a tungsten layer is presented. Two sets of wafers, one with a very rough tungsten overlayer surface and another with a smooth polished tungsten surface have been studied. It is shown that the rough tungsten surface gives rise to a very strong nonlinear behavior of the thermal-wave field.