Common-optical path self-calibrating thin film thickness measuring device and measuring method

Abstract

The present invention provides a common-optical path self-calibrating thin film thickness measuring device and measuring method. The measuring device includes a light source output module, a film thickness measurement probe module, an interference and demodulation module and an acquisition and control module; the measuring probes of the measuring device of the invention can simultaneously realize the transmission and reflection of transmitted light, the measurement of an absolute distance H between the two probes can be realized when no thin films to be measured exist; when a thin film to be measured is arranged between the two probes; an absolute distance H1 between one probe and the front surface of the thin film to be measured and an absolute distance H2 between the other probe and the rear surface of the thin film to be measured can be realized; and the thickness of the thin film to be measured can be determined according to an equation that d=H-(H1+H2). With the common-optical path self-calibrating thin film thickness measuring device and measuring method of the invention adopted, the measurement of the thickness of a transparent thin film and an opaque thin film can be realized without calibrating samples required; and since interference light beams share one optical path, influences brought by mechanical instability in a measurement system and the change of an external environment during a measurement process can be eliminated. The common-optical path self-calibrating thin film thickness measuring device and measuring method have the advantages of self-calibration, traceable measuring results, high stability and the like.

Description

technical field [0001] The invention relates to an optical measuring device, in particular to a film thickness measuring device. Specifically, it is a common optical path self-calibration film thickness measuring device. Background technique [0002] With the vigorous development of material science and technology, in order to meet the urgent needs of microelectronics, optoelectronics, new energy and other fields, thin films are used in optical engineering, mechanical engineering, communication engineering, biological engineering, aerospace engineering, chemical engineering, medical engineering and other fields. widely used. One of the core and key parameters of thin film materials is thickness, which not only plays a key role in the preparation of thin films, but also basically determines the mechanical, electromagnetic, photoelectric and optical properties of thin films. [0003] In 1961, N. Schwartz and others proposed a contact probe method that uses high-precision mec...

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Problems solved by technology

[0004] In 2013, Ma Xizhi and others from Nanjing University of Aeronautics and Astronautics disclosed an ultrasonic film thickness measuring instrument and its measurement method (Chinese patent application number: 201310198294.9). Measure the correlation characteristics of the reflected pulse to measure the thickness of the oil film; however, this method is only suitable for the measurement of the liquid mode, and different models need to be established for films with different thickness ranges, and the demodulation is difficult

In 2014, Jia Chuanwu of Shandong University and others disclosed a system for measuring film thickness by wide-spectrum optical interferometry (Chinese patent application number: 201410290494.1). Interferometer, the thickness of the film to be tested can be obtained by measuring the length of the Fabry Perot cavity before and after placing the film to be tested under the mirror. This method has a simple structure and high measurement accuracy. Under the mirror, it is easy to damage the morphology of the film surface

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