This paper explores the methodologies of real-time measurement of photoresist film thickness on silicon wafers using multi-wavelength reflection interferometry. Reflected light from the wafer's surface, containing the interference profile, is collected in-situ via a fiber optic cable and film thickness is determined in real-time via a pattern recognition algorithm. The instrumentation used to make this measurement and its application toward optimizing track performance during spin-coating and back are discussed. Data demonstrating basic thickness versus spin-time and thickness versus bake-time profiles acquired on-line without process disruption are presented along with its utilization toward minimizing process set-up and machine qualification. Moreover, the advantages of characterizing film thickness on-line and in real-time are reviewed.


Materials Science and Engineering

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