High-resolution EDS analysis of ultra-thin TaSiN diffusion barriers for Cu metallization using microcalorimetry

Microcalorimeter-based energy dispersive X-ray spectroscopy (EDS) has been used to analyze ultra-thin TaSiN films under development as ion diffusion barriers in sub-0.1 micrometer integrated circuit (IC) interconnects. The elimination of elemental peak overlaps provided by the improved energy resolution of the microcalorimeter X-ray detector is demonstrated for TaSiN films as thin as 3.5 nm. Also, variation of the electron beam (e-beam) energy is examined to reduce the X-ray generation volume relative to the TaSiN film thickness. This work demonstrates the utility of microcalorimeter-based EDS for compositional metrology of ultra-thin barrier layers for Cu metallization.