| In the microelectronics and micro-electromechanical-systems (MEMS) design and manufacturing process,now widely used by the high aspect ratio deep trench structure,the traditional measurement methods can not achieve measurements,so it requires the use of optical method to measure the critical dimension of deep trench. The degree thesis is supported by Hi-Tech Research and Development Program of China, the National Natural Science Foundation of China and Program for New Century Excellent Talents in University of China.According to the optical properties of silicon semiconductor material, it proposes model-based infrared reflectometry to measure deep trench.with infrared light through the Fourier Transform Infrared Spectrometer and formed Interference to incident into the samples, using detector to access the light reflection information and compute the critical dimension of deep trench.This thesis has used the effective medium approximation transform deep trench into the layered model with the same optical properties and adopt the Fresnel formula and transmission matrix method to simulate the deep trench reflection spectrum. Extensive comparative investigation by means of effective medium approximation (EMA) and rigorous coupled-wave analysis (RCWA) proposes a new method based on EMA but adds a dispersion corrected factor to calculate the refractive index of each effective medium. This method is not only fast in calculation but also accurate enough.Study on parameters extraction algorithm based on simulated annealing and LM algorithm, combine both to achieve the parameters extraction of the deep trenchSimulate the reflection spectrum of the standard deep trench and bottle trench by MATLAB programming , analyse how the deep trench depth, top width, bottom width, void fraction, and other geometric feature size impact the reflection spectrum.And adopt a self-designed experimental system completed a film on the measurement, and results were analyzed.
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