Thickness And Uniformity Monitoring Apparatus For Thin Films
Original Publication Date: 1979-Feb-01
Included in the Prior Art Database: 2005-Feb-19
A thickness and uniformity monitoring apparatus for thin films is shown in the drawing. The apparatus 10 includes mirrors 14 and 16 and a laser 12, for example, a He-Ne laser. The laser beam passes through an inverted telescope, consisting of lenses 18 and 20 and aperture 19, to spatially filter the beam and give a large uniform plane wave front, and then through a cylindrical lens 21 to focus the beam to a thin line or ribbon of light. The focused laser beam passes through the 90 degrees prism 22 and forms a line across the sample 24. The sample 24 is positioned on a thin film 26 of silver about 600 angstroms thick. This apparatus excites a surface electromagnetic wave (surface plasmon) on the surface of the film 26, and the image is viewed on a calibrated screen 28.