Investigation of nitrogen incorporation into manganese based copper diffusion barrier layers for future interconnect applications

Manganese silicate has been shown to be an effective copper diffusion barrier layer for potential complimentary metal-oxide-semiconductor integration, but issues arise with regard to subsequent thin film metal adhesion. In this work, X-ray photoelectron spectroscopy has been used to systematically investigate the effect of incorporating nitrogen within manganese-based films in terms of both surface chemistry and adhesion of subsequently deposited copper. Results show that while all manganese films are heavily oxidised, and the deposition of single phase Mn nitride thin films appears to be very difficult, manganese oxide films containing small amounts nitrogen are shown to improve the adhesion of the copper to the underlying dielectric. Furthermore, it is shown that the incorporation of nitrogen into the manganese films does not inhibit the formation of manganese silicate at the dielectric interface.