Cause of Aligned‐Orientation Growth of Titanium Silicide in Plasma Enhanced Chemical Vapor Deposition

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Abstract
Growth characteristics in initial stages of an aligned‐orientation growth of epitaxial C49‐structure grains selectively deposited by plasma‐enhanced chemical vapor deposition (PECVD) are studied and compared with polycrystal growth of silicides in low‐pressure chemical vapor deposition (LPCVD). PECVD was performed using gases with and without at about 700°C on (001)‐oriented Si substrates. Ti atoms diffused into the silicon from the surface in the initial growth stages. The density of Ti atoms increased and epitaxial silicide grains were first formed when the density reached that of the disilicide. In LPCVD using and , island grains of a Ti‐rich silicide and a disilicide with multiple orientations were formed in the initial stages. The Ti‐rich silicide was deposited due to the high rate of Cl reduction from by Si of the substrate and low decomposition rate. In the succeeding deposition, the decomposition rate increased and the Ti‐rich silicide was changed into the C54‐structure . The difficulty of epitaxial growth in LPCVD results from the growth of multiple silicides, island growth, and stoichiometry change. Above difference in growth features between PECVD and LPCVD is caused by a difference in behaviors of Ti diffusion into silicon. The Ti‐atom diffusion plays an important role in the aligned‐orientation growth in PECVD.

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