Interfacial reaction of Ta and Si rich tantalum silicides with Si substrate

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Abstract
Properties of tantalum silicide (TaSix) films deposited from a TaSix composite target are studied. Ta-rich (Si/Ta atom ratio, x=1.83) and Si-rich (x=2.60) films are deposited by dc magnetron sputtering on Si substrates. In Ta-rich films, a silicidation reaction occurs with annealing above 700 °C. As a result, Si composition, x, and silicide film thickness increases with consuming Si substrate. Stress changes abruptly from tensile to compressive with this reaction. This stress change leads to peeling in the Ta-rich film during the silicidation reaction. In Si-rich films, excess Si precipitates at the interface at 750 °C. However, the stress changes more gently in the Si-rich film and a more uniform TaSi2/Si interface is formed. Therefore, peeling can be avoided in Si-rich films.