Title :
Characterization of Cu Reflows on Ru
Author :
Yang, C.-C. ; Flaitz, P. ; Edelstein, D.
Author_Institution :
IBM Res., Yorktown Heights, NY, USA
Abstract :
As compared to conventional Cu reflows on Ta, lower temperature reflow anneals of Cu on Ru are achieved. Cu films are reflowed into 40-nm-wide features at an optimum temperature of 250°C with a measured activation energy of 0.8 eV. Although higher anneal temperatures can shorten the process time, they also tend to increase hollow metal defects (missing Cu within patterned features). Compared to the control electroplated samples, the reflow-annealed samples do not show bigger Cu grains in the final structure. The observed resistance reduction from the reflowed samples is attributed to higher purity within the Cu interconnects.
Keywords :
annealing; copper; reflow soldering; ruthenium; Cu; Cu reflows; Ru; activation energy; anneal temperatures; electron volt energy 0.8 eV; electroplated samples; hollow metal defects; process time; reflow-annealed samples; reflowed samples; resistance reduction; size 40 nm; temperature 250 C; temperature reflow anneals; Annealing; Copper; Electrical resistance measurement; Integrated circuit interconnections; Resistance; Surface treatment; Temperature measurement; Copper; grain size; ruthenium; surface diffusion;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2011.2161260
