A comparison of methods for accurate film thickness measurement

Effects of phase changes on reflection and their wavelength dependence in optical profilometry

The method as well as an appropriate instrumentation for measuring phase changes of reflected light is described. The phase changes on samples of Au, Al, Ag, and Cr evaporated films are measured for five wavelengths (lambda) from 442 to 633 nm, with respect to the phase change at the glass-air interface, where it should be zero. The measured results 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 for Al and Ag films are different from calculated values by ~5 degrees or a shift length of 4.4 nm at lambda = 633 nm, while those of the Cr film show large shifts as high as 16 degrees or a shift length of 9.8 nm at lambda = 442 nm.

Silver-magnesium fluoride cermet films. 1: Preparation and microstructure

We have prepared and studied seventeen thin films ranging in composition from pure silver to pure magnesium fluoride. Using mass thicknesses based on quartz crystal oscillators and physical thicknesses obtained from a stylus profilometer, we have measured the void volume fraction of the films as a function of their composition. We have shown the Ag-MgF(2) system to be capable of incorporating a high volume fraction of voids. We report on the results of electron microscope studies of the films, which show the dependence of film microstructure on composition, thickness, and the nature of its substrate.

Stylus profiling instrument for measuring statistical properties of smooth optical surfaces

A surface profiling instrument is described which produces digitized surface profiles and other statistical data. Sharp styli are available that can give height resolution of the order of 1-2 A and lateral resolution of a few tenths of a micrometer on smooth surfaces. The stylus loading can be adjusted so that no permanent marks are left on the surface. Representative surface profiles and autocovariance functions are shown for various materials, and roughnesses measured with the instrument are compared with values obtained using other techniques.