Noncontacting measurement of opaque thin films using a dual beam thermal wave probe

Abstract

A dual beam thermal wave probe has been used to measure the thickness of opaque thin films in a noncontact, nondestructive manner. The method relies on the measurement of the differential phase of two interferometrically determined photodisplacement signals. The technique does not require calibration against standard samples and can be used to determine film thicknesses from a few tens of nanometers up to several micrometers. Alternatively, if the film thickness is known, thermal material properties like diffusivity or conductivity can be determined. The conditions under which the system is expected to give the most accurate results are analyzed.

Sensitive photothermal interferometric detection method for characterization of transparent plate samples

“…Practically in the case of collinear photothermal experimental configuration, the thermal lens effect and probe beam deflection caused by the temperature gradient within the sample, 9 the photoreflectance effect caused by the surface reflectivity change, 31 and the reflected probe beam deflection and divergence caused by the surface thermoelastic deformation 32 all contribute to the total photothermal signal. Their contribution may increase or decrease the total photothermal signal, depending on the beam geometry and experimental scheme.…”

Nondestructive Analytical Tools for Characterization of Thin Titanium Silicide Films Prepared by Conventional and Direct Step Silicidation with Enhanced Transition

“…TW analysis.-TW instruments are well established in the field of nondestructive testing and material characterization. 27,28 In this method, an intense modulated light beam irradiates the sample surface and the energy dissipation creates a time-dependent response field, the so-called thermal wave. This TW follows the excitation frequency with a magnitude and a phase shift which characterize the material properties.…”

Sensitivity Enhancement by Sample Surface Coatings on Photothermal Metal Thin-Film Thickness Measurements

“…On the other hand, high measurement resolution was obtained for thin-film thickness measurements by a photothermal method. 1) But the method's instrument has disadvantages similar to other photothermal methods; it is very complicated and expensive; thickness is unobtainable if the quality of the film is uneven for various thickness samples, as well as unobtainable without material constants of the films; and obtaining wide aerial average film thickness is difficult, especially obtaining spatial distributions of thickness.…”