Determination of Thickness and Optical Properties of Tantalum Oxide Thin Films by Spectroscopic Ellipsometry

Abstract:

Tantalum oxide (Ta₂O₅) thin films were prepared, at different deposition time, by a DC reactive magnetron sputtering. During the deposition, a high-quality tantalum target was sputtered under argon and oxygen ambience on to silicon (100) and glass substrates. The prepared thin films were systematically characterized for both physical and optical properties based on spectroscopic ellipsometry (SE), and consequently confirmed by several methods. With the SE physical models, we could determine the thin film thickness as well as their inhomogeneity. The films thickness results were directly confirmed by field-emission scanning electron microscopy (FE-SEM) used to observe cross-sections, and surface profiler used to measure the physical thickness of the films. With the SE optical models, we applied both the Cauchy and Tauc-Lorentz dispersions in order to obtain the optical constants, to be directly compared with those from the Swanepoel method (SM). Our result showed that from the SE analyses, the SE physical model was obtained as the multi-layer configurations. The obtained Ta₂O₅ thin film thickness was closely related with the measured result from the FE-SEM cross-sectional micrographs and the surface profiler. For the optical characteristic, the double layer physical model was best optimized with the Tauc Lorentz dispersion model for the most accurate results. In comparison, the SM technique also demonstrated a capability to determine both the film thickness and its refractive index only from some samples. Therefore, this study proved that the SE technique successfully and accurately determine both the physical and optical properties of the Ta₂O₅ thin films.

• Periodical: Advanced Materials Research (Volume 979)
• Pages: 244-247
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.979.244
• Online since: June 2014
• Authors: Chanunthorn Chananonnawathorn*, Narathon Khemasiri, Thanat Srichaiyaperk, Benjarong Samransuksamer, Mati Horprathum, Pitak Eiamchai, Saksorn Limwichean, Kamon Aiempanakit, Pongpan Chindaudom
• Keywords: Reactive Magnetron Sputtering, Spectroscopic Ellipsometry, Sputtering, Swanepoel Method, Tantalum Oxide

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