Reflectance metrology of thin films

Abstract

This thesis investigates the application of reflectometry techniques for characterizing thin-film structures, with a focus on developing methods to analyse complex multilayer configurations. Accurate reflectance data is critical in reflectometry, therefore, the Richardson-Lucy bandwidth correction method was applied and tested on reflectance measurements of a 2-μm-thick SiO₂ layer on a silicon substrate. This evaluation assessed improvements, effects and artifacts the method might introduce on processed measured data.

In parallel, a basic model of the PillarHall chip, featuring an air gap layer, was developed and analysed. This model employs a dedicated MATLAB code based on the transfer-matrix method to simulate the reflectance spectrum and fit it to the measured data, enabling the extraction of layers’ thicknesses of the studied sample. Building on the basic model, an advanced PillarHall model was created, designed not only to estimate layer thickness but also to determine the size of specific structural features. The findings underscore the importance of accurate, bandwidth-corrected reflectance spectra, as the precision of fitted model parameters correlates directly with the spectrum quality.