Method and device for measuring thickness and refractive index of thin film

Abstract

The invention discloses a method and device for measuring thickness and refractive index of a thin film and an application thereof. The method comprises the following steps of: projecting at least three light beams onto the same point or position on the surface of a thin film sample in different incident angles, receiving intensity of a reflected light beam by an array photoelectric detector, comparing the intensity with the light intensity of an incident light beam, calculating the refractive index of each light beam, and finally fitting with a theoretical formula to obtain the thickness and the refractive index of the thin film to be measured. The device comprises a power supply, a transmission grating, a diaphragm, a condenser lens, a polarizer and a sample rotating platform are sequentially arranged along optical axis; axis of the sample rotating platform is coincided with the axis of a photoelectric detector rotating platform, wherein the diameter of the photoelectric detector rotating platform is more than the diameter of the sample rotating platform; and a photoelectric detector, a signal sampling, amplifying and AD conversion circuit and a computer which are arranged on the photoelectric detector rotating platform are sequentially connected. The method and device disclosed by the invention have the characteristics of fast measuring speed and high spatial resolution, and integrated circuits (IC) and / or functional thin-film devices can be detected in a large scale.

Description

technical field [0001] The invention belongs to the technical field of photoelectric precision measurement, and relates to a method and a device for measuring film thickness and refractive index. Background technique [0002] There are many optical methods for measuring parameters such as film thickness and refractive index, mainly including ellipsometry, interference method, prism coupling method, and spectroscopic method. These methods or technologies have their own advantages and disadvantages, and the type of film to be measured and the measurement range of parameters have certain limitations: For example, the prism coupling method (also known as the optical waveguide method) has high accuracy in measuring the refractive index of the film, but there are A certain range of measuring the refractive index of the film is generally smaller than the refractive index of the prism, and it is difficult to apply to the film thickness below 200nm; the measurement accuracy of the in...

AI Technical Summary

Problems solved by technology

These methods or technologies have their own advantages and disadvantages, and the type of film to be measured and the measurement range of parameters have certain limitations: For example, the prism coupling method (also known as the optical waveguide method) has high accuracy in measuring the refractive index of the film, but there are A certain range of measuring the refractive index of the film is generally smaller than the refractive index of the prism, and it is difficult to apply to the film thickness below 200nm; the measurement accuracy of the interferometric method is not high, and the spectral method needs at least two measurements, and the result is unstable; Using the method of measuring multi-angle polarized light reflectance to determine film parameters, such as the article "Simultaneous measurement of refrative index and thickness of thin film by polarized reflectances" by Tami Kihara et al. (Appl.Opt.1990, 29, 5069-5073) and The method provided by "Simultaneous measurement of the refrative index and thickness of thin films by S-polarized reflectances" (Appl.Opt.1992, 31, 4482-4487)" is to rotate the sample and the detector synchronously in turn to measure the polarization of different incident angles respectively For the reflectivity of light, parameters such as the thickness and refractive index of the film are obtained through theoretical fitting, so the experimental time for obtaining the reflectivity of this method is long, the spot area incident on the sample surface is large, the spatial resolution is small, and it is difficult to detect the surface Parameters of tiny structures

Images