Copper drift in low-K polymer dielectrics for ULSI metallization

This paper reports the drift of Cu ions in various low-permittivity polymer dielectrics to identify Cu barrier requirements for future ULSI integration. Bias-temperature stressing was conducted on Cu-insulator-semiconductor capacitors to investigate Cu+ penetration into the polymers. Our study shows that Cu/sup +/ ions drift readily into poly(arylene ether) and fluorinated polyimide, but much more slowly into benzocyclobutene. A thin nitride cap layer can stop the drift. A physical model has been developed to explain the kinetics of Cu/sup +/ drift.