Fixed-angle, energy-dispersive X-ray reflectivity measurement of thin Tantalum film thickness

In this work, we employed a fixed-angle, energy-dispersive x-ray reflectivity technique to obtain the thickness of thin tantalum films (examples >9 nm) within seconds using a conventional, low-energy x-ray copper or chromium source (20 kV/20 mA/400 W). We compared this fixed-angle, energy-dispersive result with more conventional fixed-energy (monochromatic source), angular-dispersive x-ray reflectivity to establish the validity of the energy-dispersive method. This x-ray technique may be particularly useful for the metrology of growing thin-barrier layers, atomic-layer passivation, and seed-layer measurements in future microelectronics applications. Currently, thickness precision is limited by modeling assumptions and the energy discrimination available from x-ray detectors.