EFFECTS OF PHASE-CHANGES ON REFLECTION AND THEIR WAVELENGTH DEPENDENCE IN OPTICAL PROFILOMETRY

The method as well as an appropriate instrumentation for measuring pha se changes of reflected light is described. The phase changes on sampl es of Au, Al, Ag, and Cr evaporated films are measured for five wavele ngths (lambda) from 442 to 633 nm, with respect to the phase change at the glass-air interface, where it should be zero. The measured result s for the Au film are in fairly good agreement with values calculated by use of optical constants from a handbook or the complex refractive index measured by an ellipsometer. The phase changes far Al and Ag fil ms are different from calculated values by similar to 5 degrees or a s hift length of 4.4 nm at lambda = 633 nm, while those of the Or film s how large shifts as high as 16 degrees or a shift length of 9.8 nm at lambda = 442 nm. (C) 1997 Optical Society of America.