A plastic-fiber-bundle-based metrology for two-dimension mapping the dissolution rate of photoresist film

A multi-port plastic-optical-fiber-bundle-based metrology is demonstrated for dynamically monitoring the thickness variation and or dissolution rate of photoresist film during photolithography process. The homemade plastic fiber bundle exhibits different structures at each end connecting to optical source, end-point probes and optical receivers, which excludes the needs of beam splitters and mirrors. Experimentally the dissolution process of the AZ1350 photoresist film at several different sites on a Cinch silicon wafer was dynamically monitored. The dissolving rate of the photoresist film was simultaneously estimated from the measured time-resolved optical interference pattern that reflected from the sample surface. The deviation on thickness of photoresist film estimated by using current apparatus were compatible with that estimated by using commercial ellipsometry. Furthermore, a two-dimensional mapping of thickness-contour of a dissolved photoresist film is also illustrated. The POFB-based probe can further gain the benefits such as anti-acid, lower loss in visible light region as compared with the silica-fiber-based one. As the fast evolution IC technology, real-time/multi-port monitoring the transient variation on thickness of thin organic (or dielectric) film during micro-lithography and etching processes by using this system is straightforward.