Measurement of Thin Film Thickness by the Crystal Resonance Method

Recent years have seen a tremendous increase in thin film activity. The electronics industry, in particular, has become increasingly active in the development and production of thin film components and complete micro-electronic circuits laid down as thin films. The principal methods of producing thin films are by chemical and electrolytic processes, and by evaporation and sputtering in vacuum. One of the problems associated with film deposition in vacuum involves the measurement of film thickness, a difficult task because: 1) the thicknesses encountered are typically measured in hundreds of angstroms; 2) the films are not physically flat; and 3) they do not display electrical or physical properties consistent with those encountered in bulk material. This thesis describes the application of a recently announced technique for measuring film thickness, and the extension of that technique to verify the growth rate of oxide coatings on metal at room temperature. The method of measurement is based on the change in resonant frequency of a vibrating quartz crystal when any mass is added to (or removed from) its active surface