Effect of post-deposition annealing on the optical and mechanical properties of amorphous tungsten oxynitride thin films

SURFACE & COATINGS TECHNOLOGY

卷:308

Article; Proceedings Paper

Nunez, O. R.¹  Tarango, A. J. Moreno¹  Hossain, K.²  Ramana, C. V.¹ 

[1] Univ Texas El Paso, Dept Mech Engn, El Paso, TX 79968 USA

[2] Amethyst Res Inc, 123 Case Circle, Ardmore, OK 73401 USA

关键词: Tungsten oxynitride;    Thin films;    Nano-indentation;    Mechanical properties;    Optical constants;   

DOI  :  10.1016/j.surfcoat.2016.07.106

来源: Elsevier

【 摘 要 】

The effect of post-deposition thermal treatment on the optical and mechanical properties of WON thin films is reported. W-O-N thin films were deposited onto silicon (100) and quartz substrates utilizing direct current (DC) sputtering under the variable flow of reactive gas mixture. Post-deposition annealing was performed at a temperature (T-a) of 400 degrees C under inert (argon) and oxygen (air) atmosphere. For annealing in an inert atmosphere, spectroscopic ellipsometry (SE) revealed changes to the dispersion profiles and magnitudes of the index of refraction (n) and extinction coefficient (k) as a result of thermal treatment. X-ray photoelectron spectroscopy (XPS) measurements revealed the loss of both nitrogen and oxygen during the annealing process in an inert atmosphere while the samples remain amorphous as evidenced in X-ray diffraction measurements. The chemical changes correlate with the changes seen in the optical constants for annealed W-O-N films. Furthermore, the physical changes during post thermal treatment probed by calculating the film-density using the Lorentz-Lorenz relation indicate a decrease in density that supports the changes in chemical composition and optical properties. Density values for annealed W-O-N films vary in the range similar to 9-12 g/cm(3), the low-to-high end of density values are noted for low and high values of nitrogen flow rate, respectively, employed during deposition. Mechanical properties of W-O-N films were demonstrated a drastic improvement as a result of post thermal treatment. The hardness values generally were improved but the W-O-N films annealed in air showed the significant improvement, up to similar to 10 GPa. XRD measurements indicated the amorphous-to-crystalline transition with m-WO3 phase as dominant component for samples annealed in an air due to the abundance of oxygen absorbed during annealing. (C) 2016 Published by Elsevier B.V.

【 授权许可】

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