Device and method for simultaneous measurement of film thickness and refractive index

Abstract

The invention discloses a film thickness and refractive index simultaneous measurement device and measurement method and belongs to the optical measurement field. The measurement device specifically includes a wide-spectrum light source output module, a narrow-linewidth laser light source output module, a film thickness measurement probe module, a demodulation interferometer module, and an acquisition and control module. According to the film thickness and refractive index simultaneous measurement device and measurement method of the invention, the output signals of the narrow-linewidth laserlight source output module are directly inputted into the demodulation interferometer module, and therefore, interference signals can share the same optical path, and at the same time, the influence of the transmitted light of laser and the multiple-reflected light of the laser in the film thickness measuring probe module on the quality of the interference signals can be avoided; and the length ofthe pigtails of a film thickness measuring probe can be controlled, so that the interference of the transmitted light of wide-spectrum light in the film thickness measurement probe module on characteristic signal peak identification can be avoided. With the film thickness and refractive index simultaneous measurement device and measurement method of the invention adopted, the non-contact measurement of the thickness and refractive index of a film can be realized with the calibration of a calibration sample not required. The film thickness and refractive index simultaneous measurement device and measurement method have the advantages of self-calibration, traceability of measurement results, high stability, simplicity in characteristic signal identification and the like.

Description

technical field [0001] The design of the invention belongs to the field of optical measurement, and in particular relates to a device and a measurement method for simultaneously measuring film thickness and refractive index. 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 widely used in optical engineering, mechanical engineering, communication engineering, biological engineering, aerospace engineering, chemical engineering, medical engineering and other fields. is widely used. The thickness of the film is not only one of the key parameters in film production, but also determines the application performance of the film in mechanical, electromagnetic, optoelectronic and optical scenarios. Accurate measurement of film thickness has always been one of the most important links in film production and application. [...

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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

[0007] In 2017, the research group of the applicant of the present invention proposed a common optical path self-calibration film thickness measurement device and measurement method (Chinese patent application number CN201710277954.0), which is realized by using a common optical path wide-spectrum optical interferometer and laser interferometer The measurement of film thickness has the advantages of common optical path and no need to calibrate the device, but this method cannot eliminate the influence of laser transmitted light, resulting in cracking of laser interference signals and affecting the accuracy of thickness measurement; in the same year, the research group of the applicant of the present invention proposed Polarization multiplexing common optical path self-calibration film thickness measurement device and measurement method (Chinese patent application number CN201710277939.6), this method can further eliminate the influence of transmitted light on the measurement results on the basis of the original advantages, but the device construction is relatively complicated

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