*Nina Hong¹, Sean Garner², Mark D. Poliks³, Jeremy Van Derslice¹, James N. Hilfiker^1
1J.A. Woollam Co., Inc., Lincoln, NE; ²Corning Research & Development Corporation, Corning NY; ³Binghamton University (SUNY), Binghamton, NY
Spectroscopic ellipsometry has been widely used for thin film characterization to measure the thickness and index of refraction. The fast measurement speed of modern ellipsometers enables in-situ monitoring and large area mapping. Spectroscopic ellipsometry is also considered for in-line metrology in roll-to-roll applications, where its non-contact and non-destructive nature combined with the fast measurement speed make it well suited for real-time monitoring. However, roll-to-roll processing presents a few challenges for in-line optical measurements. The correct configuration should be considered to ensure good data quality and robust modelling characterization. In this study, we present spectroscopic ellipsometry measurement results on thin films deposited on two different flexible substrates: isotropic flexible glass and anisotropic Polyethylene naphthalate (PEN) polymeric substrate. Different measurement conditions are compared to decide the best in-line ellipsometer configuration. Comparisons are made for data with different spot sizes, wavelength ranges, angles of incidence as well as different measurement types (e.g. reflection and transmission). The advantages and disadvantages of each ellipsometer configuration are addressed for their pertinence toward a roll-to-roll platform.