SIMULTANEOUS MEASUREMENT OF 6 LAYERS IN A SILICON-ON-INSULATOR FILM STACK USING SPECTROPHOTOMETRY AND BEAM PROFILE REFLECTOMETRY

We performed simultaneous measurements of all the layer thicknesses in six layer silicon on oxide film structures, Visible-near-infrared spe ctrophatometry was combined with beam profile reflectometry to produce enough information to discriminate between potential solutions the sp ectrometer or beam profile reflectometer alone is insufficient to solv e such a complicated film stack. Development of a robust measurement r ecipe required a new global optimization method working in parameter s paces of up to 12 parameters, The recipe obtained was applied to a 50 site mapping of the wafer. We found excellent agreement between our op tical measurement results and scanning electron micrograph data fur al l thicknesses. (C) 1997 American Institute of Physics.