A characterization method for the metal thin film

Abstract

The evanescent wave, occurred when the incident light generates total internal reflection on the interface between glass and metallic film, can raise the surface plasmon (SP) on the metallic film. SP and evanescent wave can resonate under certain angle of incidence when they have the same frequency and wave number. In this case, the power of reflection beam decreases dramatically, and the resonance peak appears in the reflection spectroscopic. The positions of resonance peaks are different when the refraction indexes of medium on the metallic film or the thicknesses of the metallic film are different. And it is found that the phase position of p-component of reflected light changes with the metal film thickness, while the phase position of s-component almost doesn’t change in the Surface Plasmon Resonance effect. S-polarized light is taken as reference and interferometry is adopted to turn the change of the phase position into the change of interference fringes position in the paper, and the film thickness can be derived from it. The simulation results indicated that, through making use of piecewise quadratic fitting on the phase data, the inaccuracy with the range of film thickness is between 30 and 80 nanometers is not more than 0.33 nm.