Simulated Annealing Simplex Algorithm Ellipsometry Data Processing Applications

Ellipsometry is an advanced technique to measure and studyoptical properties of film and material surface. Because of themerits of high precision, high speed and non-touch, there arewide applications of this technique in fields of physics, chemistry,material, biomedicine, etc. Ellipsometric data processing is animportant part of ellipsometry technique. Because theellipsometric equations are very complex and transcendentalwhich have not been inverted, the ellipsometric data inversionsfor various practical films have being always the hotspot forresearchers. The development history and status quo ofellipsometric data processing are summarized. Common problemsin iterative method of ellipsometric data processing are analyzedand an improved iterative method is presented to solve them.Combining merits of simulated annealing algorithm and simplexdownhill algorithm, a new algorithm named simulatedannealing-simplex hybrid algorithm is presented to solve theproblems of ellipsometric data inversion with single incidentwavelength. The parameters selection and error sources andcontrol of this hybrid algorithm to invert the models ofsingle-layer transparent films, single-layer absorbing films anddouble-layer transparent films are analyzed and studied. Ahorizontal sample stage ellipsometer with single incidentwavelength named HST-3 is used to measure single-layertransparent films and absorbing films, which is developed byourselves. Simulated annealing-simplex downhill hybridalgorithm is used to invert the data which are produced by HST-3ellipsometer and the experiments results show that simulatedannealing-simplex downhill hybrid algorithm is feasible andcredible in ellipsometric data inversion. Hybrid algorithm hasbeen further perfected, which makes the functions of ellipsometerwith single incident wavelength stronger and enlarged. Thus theellipsometer with single incident wavelength will get moreapplications.