Apparatus and Method for Film Thickness and Optical Constant Determination
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
A new method is described for measuring the thickness and optical properties of thin films. This method depends on the fact that the reflectivity and transmissivity of a thin film as a function of angle of incidence are strongly dependent upon the thickness and the real and imaginary indices of refraction of the media. In this method the angular reflectivity (or transmissivity) spectra is measured by illumination with a finite band of angles and detected by means of a suitable detector such as a diode array. Specific embodiments of the apparatus used to practice the method are shown in Figs. 1 and 2. In Fig. 1, narrow band, polarized and collimated radiation from a laser 1 or a filtered light source is reflected by a 50% beam splitter 2 and focused by a low f/number cylindrical lens 3 to a small focal spot on the thin film 4.