Method for adaptively measuring film thickness through white light reflectance based on Bayesian regularization algorithm

A technology of film thickness and reflectivity, which is applied in the field of optical precision measurement and signal processing, can solve the problems of general and complex algorithm accuracy and network promotion ability, and achieve the effect of reducing measurement time, reducing influence and increasing measurement speed

Inactive Publication Date: 2017-12-22
CHINA JILIANG UNIV
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Problems solved by technology

But in actual application, BP neural network is easy to fall into local minimum in the learning fitting process, and the characteristic on algorithm precision and network generalization ability is more general, for this more complex application environment involved in the present invention, then comparatively complex

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  • Method for adaptively measuring film thickness through white light reflectance based on Bayesian regularization algorithm
  • Method for adaptively measuring film thickness through white light reflectance based on Bayesian regularization algorithm
  • Method for adaptively measuring film thickness through white light reflectance based on Bayesian regularization algorithm

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Embodiment Construction

[0032] Below, the method will be explained with reference to the accompanying drawings.

[0033] 1) Use a white light emitter to emit white light from the air to the film to be tested, and obtain refracted and reflected light in the signal collection area to obtain a set of original WLRS signals;

[0034] Specifically: as attached figure 1 As shown, a beam of white light A is emitted from air to the film to be tested by a white light emitter at an incident angle α, wherein the incident angle α is less than ±5°. The light is on the upper and lower interface S 1 , S 2 Refraction and reflection occur repeatedly, and finally the light B after repeated refraction and reflection will be refracted and reflected in the signal collection area 1 , B 2 ,...,B n , and obtain a set of original WLRS signals through the phase difference of the collected light.

[0035] 2) After normalizing a group of original WLRS signals obtained in step 1, introduce them into the training set, set th...

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Abstract

The invention discloses a method for adaptively measuring film thickness through white light reflectance based on a Bayesian regularization algorithm. The method is characterized by carrying out learning fitting on signals polluted by noise in dynamic measurement through a BP nerve network using the Bayesian regularization algorithm to obtain a fit WLRS curve; and obtaining characteristic values of the fit WLRS curve, and carrying out fast and accurate measurement of the thickness of a film to be measured. Through actual measurement, the method is proved to have better anti-interference capability and a certain adaptability.

Description

technical field [0001] The invention belongs to the field of optical precision measurement and signal processing, in particular to an adaptive method for measuring film thickness of white light reflectance based on Bayesian regularization algorithm. Background technique [0002] White light reflectance spectroscopy (WLRS) technology is a method to measure the thickness of a film by using the difference in reflectance changes in the process of continuous refraction and reflection between media at different wavelengths. For its specific measurement model, see figure 1 . White light A from a white light emitter strikes the interface S between air and silicon dioxide, silicon dioxide and the substrate at a near-perpendicular angle of incidence α 1 , S 2 Refractive reflections are constantly occurring, causing a phase shift. This phase shift is related to the wavelength of light, that is to say, light of different wavelengths figure 1 There are different reflectivities in th...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/06
CPCG01B11/0625
Inventor 郑永军黄强顾海洋柳滨罗哉
Owner CHINA JILIANG UNIV
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