Detection of periodic structures through opaque metal layers by optical measurements of ultrafast electron dynamics

S. Edward*, A. Antoncecchi, H. Zhang, H. Sielcken, S. Witte, P. C.M. Planken

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We report on femtosecond optical pump-probe measurements of ultrafast electron dynamics to detect the presence of gratings buried underneath optically opaque gold layers. Electron energy diffusion and cooling are found to be strongly affected by the presence and type of metal buried below the gold layer. As a result, the spatially periodic buried grating is encoded on the electron temperature near the top surface, leading to a spatially periodic modulation of the optical properties near the gold surface from which a delayed probe pulse can be diffracted. Our measurements show that these effects may be useful for optical detection and alignment applications in semiconductor device manufacturing.

Original languageEnglish
Pages (from-to)23380-23396
Number of pages17
JournalOptics Express
Volume26
Issue number18
Early online date28 Aug 2018
DOIs
Publication statusPublished - 3 Sep 2018

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