HIGH-SPEED SPECTRAL ELLIPSOMETRY FOR IN-SITU DIAGNOSTICS AND PROCESS-CONTROL

Real-time sensors are key for flexible manufacturing environments wher e variable layer structures are processed concurrently. We have develo ped a high speed spectral ellipsometer capable of precisely measuring thicknesses and compositions of multilayer structures in situ and in r eal-time (i.e., the time frame of process changes or about one second) . This spectral ellipsometer has been integrated into several vacuum c hambers of a flexible process flow. Utilizing phase modulation, multic hannel detection, and digital signal processing techniques, less than 0.5 s is required for acquisition of 46 spectral points. Fast numerica l algorithms and processor are used for reducing measured spectral ell ipsometric data to physical parameters (i.e., thicknesses and composit ions), in real time based on a ''standard model'' approach. Implementa tions of spectral ellipsometric sensing in rapid thermal oxidation and remote plasma etch are described. For thermally activated processes s uch as oxidation, temperature dependent dielectric functions have been employed for analyzing samples at process temperatures as high as 110 0-degrees-C. Multilayer combinations Of Si3N4, SiO2, Si3N4 plus SiO2 m ixtures, and polycrystalline Si have been monitored and thicknesses co ntrolled.