NONCONTACTING MEASUREMENT OF OPAQUE THIN-FILMS USING A DUAL-BEAM THERMAL-WAVE PROBE

A dual beam thermal wave probe has been used to measure the thickness of opaque thin films in a noncontact, nondestructive manner. The metho d relies on the measurement of the differential phase of two interfero metrically determined photodisplacement signals. The technique does no t require calibration against standard samples and can be used to dete rmine film thicknesses from a few tens of nanometers up to several mic rometers. Alternatively, if the film thickness is known, thermal mater ial properties like diffusivity or conductivity can be determined. The conditions under which the system is expected to give the most accura te results are analyzed.