AVS 53rd International Symposium
    Thin Film Thursday Sessions
       Session TF-ThM

Paper TF-ThM2
CVD of Titanium Diboride using Single Source Precursor

Thursday, November 16, 2006, 8:20 am, Room 2022

Session: Fundamentals in Thin Film Deposition
Presenter: N. Kumar, University of Illinois Urbana-Champaign
Authors: N. Kumar, University of Illinois Urbana-Champaign
Y. Yang, University of Illinois Urbana-Champaign
W. Noh, University of Illinois Urbana-Champaign
G. Girolami, University of Illinois Urbana-Champaign
J. Abelson, University of Illinois Urbana-Champaign
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TiB@sub 2@ is a mechanically hard, metallic ceramic with a bulk melting temperature of 3220 °C and electrical resistivity of 10 @micro@@ohm@-cm. Thin films of TiB@sub 2@ have been used as wear resistant protective coatings in magnetic storage media and other applications. TiB@sub 2@ has also been investigated as a possible liner material and/or contact electrode in microelectronics. CVD growth of TiB@sub 2@ can be accomplished using halide based precursors, but this process is inherently corrosive and requires substrate temperatures in excess of 600°C. Girolami et al. previously synthesized the halogen free, single source precursor Ti(BH@sub 4@)@sub 3@dme. This talk will focus on the CVD of TiB@sub 2@ films using this precursor, including the deposition kinetics, film microstructure, diffusion barrier properties and conformality on trench shaped substrates. Films were grown at substrate temperatures ranging from 170 to 800 °C. Films grown at lower temperatures are X-ray amorphous whereas films grown at 800°C are polycrystalline. Film growth starts at temperatures as low as 170 °C on SiO@sub 2@ substrates. The growth rate is 2 nm/min below 200°C, 4 nm/min for intermediate temperatures, and 2.5 nm/min at 800 °C. There is no nucleation delay as measured by in situ ellipsometry, even at the lowest growth temperatures. For the lowest and highest growth temperatures, the films are nearly stoichiometric and have C and O contents lower than 5 at. % as measured by AES. In the intermediate temperature range the films have B/Ti ratio < 2 and the C and O contents are > 10 at. %. Low temperature films have a dense columnar microstructure as evaluated by SEM. For a 40 nm thick film, the RMS roughness by tapping mode AFM is 1.5 nm. The electrical resistivity is 265 @micro@@ohm@-cm. The film also performed well as a diffusion barrier to prevent Cu diffusion into Si for temperatures as high as 600 °C.