Quantitative secondary ion mass spectrometry analysis of contaminants in TaSi2 thin films

Secondary ion mass spectrometry has been used to identify and quantify contaminants in TaSi2 thin films. Quantification was established for 31 elements by the analysis of ion implants into TaSi2 layers. The results are tabulated in terms of useful yield and relative sensitivity factor. The data follow the same useful yield versus ionization potential relationship noted for a Si matrix. Contamination, in films deposited by cosputtering from pure Ta and Si targets in a multiwafer rotating hemisphere system, was correlated to metallic machine components. Analysis of films from more than 75 targets used in a composite target single-wafer system showed that the metallic contamination was caused by the presence of impurities within the target. The mobility of the detected elements was investigated by analyzing samples as deposited and after anneal. Al and B showed significant redistribution after anneal, but most elements, including Fe, remained stationary in the TaSi2. The contamination and diffusion results were useful in analysis of product problems and in the determination of specifications for TaSi2 targets