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Title:Solution to the inverse problem of optical scatterometry
Author(s):Cohen, Lucas
Contributor(s):Goddard, Lynford L.
Subject(s):optical scatterometry
inverse problem of optical scatterometry
FDTD solutions
Abstract:When fabricating new integrated devices, the need for an accurate non-invasive method of characterization becomes prevalent. Research into periodic nanostructures has resulted in our ability for greater control of light’s propagation and interaction with materials. Specifically, among many other applications in nanotechnology these structures can be used for analog to digital conversion, associative storage, beam deflectors and reflectors, and beam expanders. In this work, optical scatterometry methods such as ellipsometry are used to record the diffraction pattern of a periodic nanostructure. The inverse problem is to use this diffraction pattern in conjunction with simulations to reconstruct the geometry of the periodic nanostructure. The inverse problem has been solved iteratively using various optimization algorithms paired with finite difference time domain (FDTD) software or other forward modeling techniques. The least squares method of optimization along with Lumerical’s FDTD Solutions software will be utilized throughout this thesis to provide a solution to the inverse problem. The results will be compared to the other methods of characterization commonly used today.
Issue Date:2018-05
Date Available in IDEALS:2018-05-23

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