Measurement of thin film interfacial surface roughness by coherence scanning interferometry

Abstract

Coherence Scanning Interferometry (CSI), which is also referred to as scanning white light interferometry, is a well-established optical method used to measure the surface roughness and topography with sub-nanometer precision. One of the challenges CSI has faced is extracting the interfacial topographies of a thin film assembly, where the thin film layers are deposited on a substrate, and each interface has its own defined roughness. What makes this analysis difficult is that the peaks of the interference signal are too close to each other to be separately identified. The Helical Complex Field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally conceived for the measurement of thin film thickness. In this paper, we verify a new technique, which uses a first order Taylor expansion of the HCF function to determine the interfacial topographies at each pixel, so avoiding a heavy computation. The method is demonstrated on the surfaces of Silicon wafers using deposited Silica and Zirconia oxide thin films as test examples. These measurements show a reasonable agreement with those obtained by conventional CSI measurement of the bare Silicon wafer substrates.

Quantitative imaging of the complexity in liquid bubbles’ evolution reveals the dynamics of film retraction

“…Currently, different techniques for quantitative phase imaging (QPI) are used to measure the thickness of transparent three-dimensional (3D) objects with one dimension thinner than the other two (films) 10,11 . In particular, interferometry is routinely used for the study of thin fluid films and surface topology, using both monochromatic and white light 12,13 . Interferometry measures the intensity of fringes produced by the interference of light reflected at the two interfaces of a thin film.…”

Correlation between surface scaling behavior and surface plasmon resonance properties of semitransparent nanostructured Cu thin films deposited via PLD

“…It is a non-destructive, fast and accurate technique which is applicable for all types of the lm including reecting as well as nonreecting, former of which can also be analyzed by optical techniques. 9,23,24 From the analysis of surface morphology, its scaling behavior and growth model can be predicated ex situ which is not only helpful is understanding the nucleation process but also plays an important role in correlating with the physical properties of the thin lm [25][26][27][28][29] In the present work, surface scaling behavior of nano structured Cu thin lms, grown onto the glass substrate at its soening temperature via pulsed laser deposition (PLD) technique, as a function of deposition time is presented. The height-height correlation function (HHCF) and power spectral density function (PSDF) were extracted from AFM images for the estimation of growth exponents a, b and 1/z.…”

Robust, Transparent Hybrid Thin Films of Phase-Change Material Sb2S3 Prepared by Electrophoretic Deposition

“…The presence of these peaks is often attributed to high-quality films, with uniform thicknesses and without significant scattering or absorbance in the region of interest. 64,65 This transparency enables interference between the incident and reflected light leading to the presence of the absorbance peaks in the spectra. 66 The continued presence of the peaks through multiple deposition steps implies that the films deposited through multiple steps can be treated as a single large layer of the deposited material, rather than as multiple small layers of the antimony trisulfide and PEI.…”