案例九：計量學

2019/08/07

Sample Setup: Metrology

Overview

A thin film on a substrate can act as an etalon, creating an interference pattern superimposed on the surface reflectivity when viewed in reflection. The spacing of the patterns sinusoidal peaks, when combined with the refraction index of the material, can be used to calculate the thickness of the material.?

Spectrometer

The USB4000-VIS-NIR (350-1000 nm) is ideal for reflectometry of thin films. The spectrometer is preconfigured with Grating #3, which is blazed at 500 nm; an OFLV-350-1000 Filter to eliminate second- and third-order effects; and a 25 m slit for optical resolution of ~1.5 nm (FWHM).

Sampling Optics

The R400-7-VIS/NIR Reflection Probe positioned at 90? measures specular reflectance from surfaces such as thin films. An LS-1 Tungsten Halogen Lamp and a STAN-SSH High-reflectivity Specular Reflectance Standard complete the sampling setup.

Measurements

Spectra observed in our operating software reveal oscillations caused by optical interference within the layers of the thin film substrate. Analysis of the wavelength position of the minima or maxima can determine either the thin films thickness (with the known refractive index of the film) or its refractive index (with the known film thickness). Keep in mind that the thickness of samples may not be uniform; we recommend measuring several locations on the film.

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