Thin film thickness measurements using Scanning White Light Interferometry
journal contributionposted on 17.12.2014, 14:19 by Bianca Maniscalco, Piotr Kaminski, Michael Walls
Scanning White Light Interferometry is a well-established technique for providing accurate surface roughness measurements and three dimensional topographical images. Here we report on the use of a variant of Scanning White Light Interferometry called coherence correlation interferometry which is now capable of providing accurate thickness measurements from transparent and semi-transparent thin films with thickness below 1 μm. This capability will have many important applications which include measurements on optical coatings, displays, semiconductor devices, transparent conducting oxides and thin film photovoltaics. In this paper we report measurements of thin film thickness made using coherence correlation interferometry on a variety of materials including metal-oxides (Nb2O5 and ZrO2), a metal-nitride (SiNx:H), a carbon-nitride (SiCxNy:H) and indium tin oxide, a transparent conducting oxide. The measurements are compared with those obtained using spectroscopic ellipsometry and in all cases excellent correlation is obtained between the techniques. A key advantage of this capability is the combination of thin film thickness and surface roughness and other three-dimensional metrology measurements from the same sample area.
The authors are grateful to EPSRC and TSB for funding. We are also grateful to Mr Daniel Mansfield and his colleagues at Taylor Hobson Ltd for the collaboration in this study and for funding a studentship for Biancamaria Maniscalco.
- Mechanical, Electrical and Manufacturing Engineering
- Centre for Renewable Energy Systems Technology (CREST)