Evaluation of surface analysis methods for characterization of trace metal surface contaminants found in silicon integrated circuit manufacturing

Abstract

We report a preliminary investigation of surface analytical methods used to evaluate trace metal contaminants on silicon wafer surfaces. The methods discussed include sputter induced postionization methods, backscattering spectrometry, total reflection x-ray fluorescence, and a sample preparation method known as vapor phase decomposition. In order to initiate the evaluation, a series of silicon wafers was dosed with transition metal contaminants Cu and Fe and then analyzed with total reflection x-ray fluorescence, sputter induced resonant ionization spectroscopy, and heavy ion backscattering spectroscopy. One wafer with low concentrations of Fe was analyzed by time of flight secondary ion mass spectrometry. As a result of this study, we are pursuing improved capability in several areas including standards. Heavy ion backscattering spectrometry is suggested as a means of verifying surface dosed silicon wafer standard.