1%2E4978066.pdf (2 MB)
Download fileMeasurement of thin film interfacial surface roughness by coherence scanning interferometry
journal contribution
posted on 2017-03-31, 13:20 authored by Hiro Yoshino, Ali AbbasAli Abbas, Piotr M. Kaminski, Roger Smith, Michael WallsMichael Walls, D. MansfieldCoherence 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.
Funding
The authors are grateful to RCUK for financial support through the SuperSolar Hub (EPSCR Grant No. EP/J017361/1).
History
School
- Mechanical, Electrical and Manufacturing Engineering