APPROACH FOR A 3-DIMENSIONAL ON-CHIP QUANTIFICATION BY SECONDARY-ION MASS-SPECTROMETRY ANALYSIS

An attempt to perform a three-dimensional (3D) quantitative evaluation of the complete sample volume sputter removed in a secondary-ion mass spectrometry analysis is described. Using a focused (similar to 3 mu m) 7 keV Cs+ primary-ion beam and detecting sputtered MCs+ ions (M sta nds for any sample element), a vertical Si-metal-oxide-semiconductor t ransistor structure (with a lateral size of similar to 40 mu m and a t otal vertical dimension of similar to 3 mu m) was analyzed by image de pth profiling. Elemental concentrations of these micrographs were deri ved from relative sensitivity factors and the pertinent depth informat ion in the 3D sample (data) volume could be estimated by utilizing the se factors and an approximation of the atomic densities. The specimen' s surface topography both in the pristine state and upon completion of the sputter depth profile was recorded by two-dimensional stylus prof ilometry. By these means, a reconstruction of the sample volume eroded during the analysis appears feasible at a lateral resolution of a few mu m and an in-depth resolution of about 10 nm. (C) 1997 American Vac uum Society.