Method for detecting optical constant and thickness of mono-layer optical film

Abstract

A method for detecting the optical constant and thickness of a single layer optical thin film relates to a method for detecting the parameters of an optical thin film. The invention provides a method for quickly detecting the optical constant and thickness of a single layer optical thin film through calculation at one time. The method comprises the steps of measuring a transmitted spectrum: measuring the transmitted spectrum of the single layer optical thin film without deducting a substrate in the condition of normal incidence by using a spectrophotometer; selecting the data of transmissivity: selecting the data of transmissivity on the transmitted spectrum and substituting the data of transmissivity into an evaluation function; conducting reversion solution adopting the simulated annealing algorithm to conduct the reversion solution for the evaluation function; and analyzing the result: analyzing the returned result by the algorithm by recovering the transmitted spectrum. The algorithm has more excellent overall performance, the returned solution magnitude order is smaller, and the tempering and annealing help the return of multiple solutions, so as to know the situation of the evaluation function. The measurement software of the spectrophotometer can be combined with the method, thereby directly reading the data of transmissivity to conduct the reverse solution and widening the application range of the spectrophotometer. The method has potential commercial value.

Description

technical field [0001] The invention relates to a method for detecting parameters of an optical film, in particular to a method for detecting the optical constant and thickness of a single-layer optical film. Background technique [0002] Transmission spectroscopy is to obtain the optical constant and thickness of a single-layer optical film (ie, the refractive index n 2 , extinction coefficient k 2 and thickness d), the key to its realization lies in the inverse optimization calculation of the established objective evaluation function (Evaluation Function). However, the evaluation function is an extremely complex function with respect to the parameters to be sought. It is difficult to calculate the partial derivative of the expression, and it has multiple extremely small peaks, which are steep, and the size of each minimum value is very close to the minimum value. [0003] Liu Xicheng et al. (Liu Xicheng, Wang Zhiheng, Liao Qingjun, Lai Chengjun. Using transmission spectr...

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Problems solved by technology

However, since this method selects 3 transmittance data to solve 3 parameters to be obtained, multiple sets of solutions will be obtained for the inversion solution. Among them, only the transmission spectrum recovered from the true solution is consistent with the measured transmission spectrum, and the other solutions are false solutions; For the complexity of the evaluation function of the transmission spectroscopy method, the algorithm cannot remember the optimal solution that has appeared in the search process, cannot reach the "trough" at the minimum value, and cannot truly reflect the characteristics of the evaluation function with multiple minimum peaks

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