Improvement of the reliability of a Cu/W-N/SiOF multilevel interconnect by inserting plasma enhanced chemical vapor deposited W-N thin film

Abstract

We have investigated the characteristics of a Cu/W-N/SiOF multilevel interconnect. The resistivity and surface roughness of the Cu film on a W-N/SiOF/Si substrate are better than those of the Cu film on a SiOF/Si substrate after annealing at 500 degreesC for 30 min. These results are due to the W-N thin film inserted between the Cu and SiOF because the surface energy of the W-N film is greater than that of the SiOF film, which improves the wettability of Cu on the NV-N film and prevents the agglomeration of the Cu film during the annealing process. Also, the stress evolution, current-voltage (I-V) characteristics and Rutherford backscattering (RBS) spectra reveal that the Cu/W-N/SiOF/Si interconnect has lower tensile stress and better electrical proper-ties than the Cu/SiOF/Si interconnect, which is due to the stress relaxation and the improvement of the bar-Her performance as a result of inserting the NV-N thin films.