Effects Of Oxide And Roughness Layer On The Polarization Characteristics Of Specular Reflection Of Micro-structure Surfaces

When the geometrical parameter scale of micro-structure is comparable to the incident wavelength, the micro scale effect which is diverse to the traditional thermal radiation theory(based on geometrical optics) is generated. The radiation characteristics should be obtained by the Maxwell equations. Previous study mainly focused on the energy transmission, and developed the theory of surface plasmon polarization(SPP) and magnetic polarization(MP). This thesis mainly investigates the radiative polarization characteristics of the micro-structure surface via calculating the electromagnetic field of the micro-structure region. The key point of the study is to research the influence of the oxide layer and roughness on ellipsometric parameters.In this paper, the effect of thickness and position of oxide layer on the ellipsometric parameters of one-dimensional aluminum rectangular grating surface is studied with one-dimensional rigorous coupled-wave analysis(RCWA) method. When the oxide layer is uniform, the ellipsometric parameters vary, and the peaks and valleys of ellipsometric parameters lead to red shift with increasing oxide thickness.When the oxide layer is not uniform, the effect on the ellipsometric parameters of the oxide layer on the top and side wall of the ridge and bottom of the groove is different, and the ellipsometric parameters of the oxide layer on different positions are sensitive to the different incident wavelength. If ellipsometric parameters are substituted into the Mueller matrix of specular reflection, the three independent elements of the matrix shift with the variation of the thickness and position of the oxide layer and the incident wave length. Its variation trend and numerical value are more obvious than those of the ellipsometric parameters. Hence the accuracy is higher and maneuverability is better of the Muller matrix in the actual ellipsometry.The influence of the root-mean-square(RMS) roughness and autocorrelation length of the two dimensional silicon on the ellipsometry parameters is studied in the case of different incident wave lengthes and incident angles with three-dimensional finite-difference time-domain(FDTD) method. The results show that the bigger the RMS roughness and the smaller the autocorrelation length is, the larger the deviation of the ellipsometry parameters from those of the smooth silicon surface becomes. When the wavelength of incident wave is smaller or the incident angle is near the Brewster angle, this deviation is more obvious.The difference of the optical constants between calculated by the ellipsometry parameters of rough surface and those of smooth surface gets larger when the RMS roughness becomes larger and the autocorrelation length and incident wavelength becomes smaller. But the optical constants calculated by the ellipsometry parameters of rough surface does not change with the incident angle.