Measurement and control of a residual oxide layer on TiSi2 films employed in ohmic contact structures
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An inadvertent oxide layer is formed on a titanium disilicide (TiSi2) film following various wet and dry processes in a manufacturing environment. The use of H2SO4:H2O2:H2O (1:1:5) as a wet etch for excess Ti metal, prior to the high temperature anneal used to form a subsequent TiSi2 layer, is identified as the source of the undesired oxide via multiwavelength spectroscopic ellipsometry and Auger electron spectrometry studies. This inadvertent oxide layer on TiSi2 is shown to form bad electrical contacts and is a contributing source to large standby currents in polysilicon gate shunts. Spectroscopic ...