Two-Color Etch Monitoring Technique
Original Publication Date: 1979-Jan-01
Included in the Prior Art Database: 2005-Feb-19
If an etching layer is illuminated by monochromatic, coherent light, the reflected light suffers periodic variations in intensity due to wellknown thin-film interference effects. If the sample is illuminated with two distinct frequencies of light, so that an interference function is obtained for each of the two frequency values, it is possible to determine the thickness of the etching layer and the material etch rate in real time.