Simultaneous Reflectometry And Interferometry For Measuring Thin-Film Thickness And Curvature

Abstract

A coupled reflectometer-interferometer apparatus is described for thin-film thickness and curvature characterization in the three-phase contact line region of evaporating fluids. Validation reflectometry studies are provided for Au, Ge, and Si substrates and thin-film coatings of SiO2 and hydrogel/Ti/SiO2. For interferometry, liquid/air and solid/air interferences are studied, where the solid/air samples consisted of glass/air/glass wedges, cylindrical lenses, and molded polydimethylsiloxane lenses. The liquid/air studies are based on steady-state evaporation experiments of water and isooctane on Si and SiO2/Ti/SiO2 wafers. The liquid thin-films facilitate characterization of both (i) the nano-scale thickness of the absorbed fluid layer and (ii) the macro-scale liquid meniscus thickness, curvature, and curvature gradient profiles. For our validation studies with commercial lenses, the apparatus is shown to measure thickness profiles within 4.1%-10.8% error.

Publication Date

5-1-2018

Publication Title

Review of Scientific Instruments

Volume

89

Issue

5

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1063/1.5021704

Socpus ID

85047768072 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85047768072

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