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Citation |
Kim SH, Oh SS, Kim HM, Kang DH, Kim KB, Li WM, Haukka S, Tuominen M. Journal of the Electrochemical Society 2004; 151(4): C272-C282. |
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Copyright |
(Copyright © 2004) |
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DOI |
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PMID |
unavailable |
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Abstract |
The properties of WNxCy, films deposited by atomic layer deposition (ALD) using WF6, NH3, and triethyl boron were characterized as diffusion barriers for copper metallization. The films deposited at 313°C showed resistivity of about 350 μΩ cm with a density of 15.4 g/cm3. The film composition measured by Rutherford backscattering spectrometry showed W, C, and N of approximately 48, 32, and 20 atom %, respectively. Transmission electron microscopy analyses showed that the as-deposited film was composed of a face-centered-cubic phase with a lattice parameter similar to both β-WC1-x and β-W2N with an equiaxed microstructure. The film kept its nanocrystalline microstructure until annealing at 700°C, although some amount of simple hexagonal α-WC was identified to be formed and the β-W2N phase disappeared. As the annealing temperature increased to 800°C, relatively larger grains of body-centered-cubic W were newly formed with smaller grains of hexagonal-close-packed α-W2C or α-WC. All the phenomena are related to nitrogen release after annealing at 700 and 800°C. The results of diffusion barrier performance between Cu and Si analyzed by X-ray diffractometry showed that ALD-WNxCy film (12 nm) failed only after annealing at 700°C for 30 min by the formation of copper suicide, while the sputter-deposited Ta (12 nm) and ALD-TiN (20 nm) films failed at 650 and 600°C annealing, respectively. It is thought that the superior diffusion barrier performance of ALD-WNxCy, film is the consequence of both the formation of equiaxed microstructure and the high-density nature of the film. © 2004 The Electrochemical Society. Language: en |
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Keywords |
Copper; Chemical vapor deposition; Thin films; X ray diffraction; Transmission electron microscopy; Diffusion in solids; Microstructure; Nanostructured materials; Rutherford backscattering spectroscopy; Diffusion barriers; Physical vapor deposition; Metallizing; Annealing temperatures; Atomic layer deposition (ALD); Electrodeposition; Precursors |