Characterization of chemically-deposited NiB and NiWB thin films as a capping layer for ULSI application

NiB and NiWB films fabricated by electroless deposition were evaluated aiming for the application to a metal cap in the copper interconnects technology. The content of B and W was varied by adjusting the concentration of components in electroless deposition baths in order to clarify the effect of co-deposited element on thermal stability of the films. The thermal stability was evaluated by Auger electron spectroscope, X-ray diffractometer (XRD) and sheet resistance measurement. By measuring the variation in sheet resistance with annealing temperature, it was confirmed that the NiB films showed good thermal stability up to 450 °C, whereas the NiWB films deteriorated at 300 °C. The effect of co-deposited element was discussed based on the results obtained by XRD as well as that of sheet resistance measurement.