AVS 47th International Symposium
    Surface Science Friday Sessions
       Session SS+MC-FrM

Paper SS+MC-FrM2
Characterization of Hf and Zr Oxides, Silicides and Silicates, Formed on the (0001) Surfaces of HfB@sub 2@ and ZrB@sub 2@, by AES, XPS, LEED and STM

Friday, October 6, 2000, 8:40 am, Room 209

Session: Characterization of Oxides and Thin Films
Presenter: R. Singh, University of Illinois at Chicago
Authors: R. Singh, University of Illinois at Chicago
Y. Paderno, Academy of Sciences of Ukraine
T. Tanaka, National Institute for Research in Inorganic Materials, Japan
M. Trenary, University of Illinois at Chicago
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Transition metal (TM) diborides have comparable and often higher degrees of hardness, chemical inertness and thermal stability than their nitride and carbide counterparts. Therefore, TM-diborides are attractive for the same type of applications as nitrides and carbides such as for hard coatings and diffusion barriers. In order to explore their usefulness as diffusion barriers and gate dielectrics, a series of experiments with silicon were performed. Silicon was deposited by the UHV-CVD of silane gas on clean and oxygen covered HfB@sub 2@ and ZrB@sub 2@(0001) surfaces. On the clean surfaces, HfSi@sub 2@ and ZrSi@sub 2@ were formed. A p(2x2)R30° LEED pattern was observed. The structure of Si on the surfaces was also investigated with STM. On the oxygen covered surfaces, silicates were formed. Oxidation of the crystals leads to the formation of HfO@sub 2@ and ZrO@sub2@, which both exhibited a (3x3) LEED pattern at a high exposure (5 L) and a p(2x2)R30 pattern at a low exposure (0.5 L). Information gained from exposure of oxygen to ZrB@sub 2@ was crucial in interpreting the O 1s region in HfB@sub2@, which partially overlaps with the Hf 4s peak.