THERMALLY STABLE TERNARY TITANIUM-TANTALUM SILICIDE FORMATION ON POLYCRYSTALLINE SILICON

Abstract

A material for thermally stable self-aligned silicide technologies has been developed using sequentially deposited Ti/Ta on polycrystalline silicon. At lower annealing temperatures below 1000-degrees-C two separate phases were found by cross-sectional transmission electron microscopy to exist in the form of bilayer TiSi2/TaSi2. The formation of a ternary phase (TiTa)Si2 has been observed at a higher temperature of 1000-degrees-C. Consequently, the ternary (TiTa) Si2 layer could be kept extremely flat, with a sheet resistance of 5 OMEGA/square, even after 1000-degrees-C, 30 min annealing. Cross-sectional transmission electron micrographs of the structure clearly reveal that no agglomeration occurs during the heat treatment.