Modelling spectral absorptance of patterned wafers

Abstract

This paper presents a parametric study of the radiative properties of silicon patterned wafers, considering the effect of wavelength and polarisation. The finite-difference time-domain (FDTD) method has been employed to examine the effect of various trench and gate sizes on the spectral absorptance via numerically solving the Maxwell’s equations. The effective medium theory (EMT) was also used to help explain the absorptance prediction. In the cases with trench size variation, clear interference effects were shown at long wavelengths for the TE wave, but the multiple reflection effect started at a much shorter wavelength for the TM wave. In the cases with polysilicon gate variation, while the gate sizes were very small compared to wavelength, the results showed rather unusual phenomena. The effects of the diffraction, wave interferences on the spectral absorptance were also discussed. This work is of great importance for optimisation of advanced annealing techniques in semiconductor manufacturing.