Inc.) rotating compensator ellipsometer equipped with an Xe lamp. To enable operando measurements, the ALD reactor was equipped with a modified lid with two quartz windows that allow the incident light to reach the sample and the reflected light to be detected at a 70° angle with respect to the normal of the substrate plane. The assembly of the spectroscopic ellipsometer on top of the ALD reactor is shown in Figure . Ex-situ SE measurements were performed at a fixed 75° incidence angle. The SE data were collected across a wavelength range spanning from 250 to 1000 nm with an acquisition time of 1.6 s. The data were analysed using version 2.3 of the EASE software package (J.A. Woollam Co. Inc). The thickness and refractive index of the polymer films during and after the SIS process were determined using a film stack model composed by a polymer layer on top of the thin SiO2 film naturally formed on the surface of the Si substrate. A Cauchy layer model was used for the polymer layer. For each sample, the thickness of the native SiO2 layer on top of the Si substrate was measured before spin casting and kept fixed during the analysis of the SE data following a procedure that is described in details in previous publications. X-ray Photoemission Spectroscopy: XPS measurements were performed using a PHI 5600 instrument equipped with a monochromatic Al K x-ray source (1486.6 eV) and a concentric hemispherical analyser. The spectra were collected at a take-off angle of 45°. Low resolution spectra were acquired with a pass energy of 93.9 eV. High resolution spectra were acquired with a pass energy of 11.75 eV. Calibration of the spectrometer was accomplished using polycrystalline gold, silver, and copper samples. The binding energies of the Au 4f7/2, the Ag 3d5/2, and the Cu 2p3/2 core lines were determined to be 84.0 eV, 368.3 eV, and 932.7 eV, respectively. The analysis of the XPS spectra was performed using the Winspec software. To correct the energy shift induced by charging of the polymer films during the XPS measurements, the C 1s core level originated by the carbonyl group was used. The binding energy of this C 1s signal was set to 289 eV. The high resolution spectra were fitted using Shirley background and Voight functions to identify the different core level signals.