Fig. 2: Subsurface nano-FTIR spectroscopy experiments on well-defined multilayer samples. | Nature Communications

Fig. 2: Subsurface nano-FTIR spectroscopy experiments on well-defined multilayer samples.

From: Subsurface chemical nanoidentification by nano-FTIR spectroscopy

Fig. 2

a Schematics of the experiment and PMMA/PS test sample, including the topography line profile of a d2 = 85 nm-thick PS layer covering the t2 = 59.4 nm-thick PMMA layer on Si. b Reference nano-FTIR phase spectra recorded on thick PMMA and PS layers. c Subsurface nano-FTIR phase spectra of PMMA at different depths d2 below PS (average of 50 spectra (80 spectra for d2 ≥ 85 nm), 30 s acquisition time per interferogram, ×128 zero filling, 17 cm−1 spectral resolution). Black arrows in c indicate the spectral peak shift \({\mathrm{\Delta }}\omega _3^{{\mathrm{max}}}\).

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