Optical field simulation of nanoscale structures on wafer surfaces based on microscopic imaging

Periodic arrays of nanoscale structures on wafer surfaces can be fabricated using micro- and nano-fabrication processes. By changing the morphology and arrangement of array structures, precise control of light can be achieved, enabling the functionality of various optical devices. The paper simulates the nanoscale array structures on the wafer surface using Finite-Difference Time-Domain (FDTD) method and conducts microscopic imaging. After wavelength optimization, it was found that for the single-layer SiO₂ array structure on the wafer surface, with shorter illumination wavelengths and larger objective numerical apertures, the characteristic information of the SiO₂ structure becomes more prominent in the microscopic imaging. However, for the multi-layer SiO₂-Si₃N₄-SiO₂ array structure on the wafer surface, the illumination source no longer follows the principle that shorter wavelengths and larger numerical apertures result in better imaging quality. Instead, the optimal imaging quality is achieved with illumination wavelengths in the range of 230nm-260nm and a numerical aperture of 0.55 for the objective lens. Therefore, in practical testing, appropriate illumination wavelengths and numerical apertures for the objective lens should be selected to achieve the best imaging quality.