Thin film thickness measurement method and system

Abstract

The invention discloses a thin film thickness measurement method and system. The thin film thickness measurement system comprises a lighting optical device, an imaging optical device and a thin film thickness analyzing device, and is characterized in that the lighting optical device is used for generating a cone-shaped beam and projecting the cone-shaped beam to a point on the thin film surface of a sample; the imaging optical device comprises a focusing lens and an image acquisition module; the focusing lens projects light reflected from the surface of the sample to the image acquisition module according to the sequence of an incidence angle from small to large, the image acquisition module detects to acquire reflection intensity information of the beam at the surface of the sample and builds a relation curve between the reflectivity and the incidence angle according to the reflection intensity information; and the thin film thickness analyzing device builds a function of the reflectivity and a refraction angle cosine value by utilizing the relation curve between the reflectivity and the incidence angle and a Snell's law, and acquires the thin film thickness of the sample through performing Fourier transform and analysis on the function. The thin film thickness measurement system is not only high in measurement accuracy, but also simple, compact and stable in light path, low in cost and easy to realize online measurement.

Description

technical field [0001] The invention relates to the field of photoelectric precision measurement, in particular to a film thickness measurement method and system. Background technique [0002] In the film thickness measurement method, the optical method is one of the most widely used methods, which has the advantages of non-contact, high sensitivity and high precision, mainly including ellipsometry (ellipsometry), spectroscopy and reflection angle distribution Law. Among them, the ellipsometry has high test sensitivity and precision, but it is easily affected by various parameters. Various errors of the system, environmental noise, sample surface roughness, differences between the film to be tested and the mathematical dispersion model, etc. will cause the measurement The stability of the result becomes worse; the spectroscopic method is based on the interference theory of light, and calculates the thickness and optical constants of the film by measuring the curve of reflec...

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is that in the existing method of measuring film thickness by monochromatic light interference effect, it is difficult to obtain fringes correctly by means of fringe counting when the reflectance of the film is low and the signal-to-noise ratio of the obtained reflectance signal is relatively small. cycle information, thereby reducing the problem of the accuracy of the entire film thickness measurement

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