Ins-situ Film Thickness Measurements for Real-time Monitoring and Control of Advanced Photoresist Track Coating Systems

This paper will explore 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 towards optimizing track performance during spin-coating and bake will be discussed, Data demonstrating basic thickness versus spin-time and thickness versus hake-time profiles acquired on-line without process disruption will be presented along with its utilization towards minimizing process set-up and machine qualification. Moreover, the advantages of characterizing film thickness on-line and in real-time will be reviewed.