Prediction of stress induced voiding reliability in Cu damascene interconnect by computer aided vacancy migration analysis

The method of computer aided vacancy migration analysis has been developed to predict the stress induced voiding (SiV) reliability. In this method, distribution of hydrostatic stress was calculated by the finite element analysis (FEA), and vacancy concentration distribution was calculated by the finite difference analysis (FDA). In this paper, SiV acceleration tests were conducted in various widths of Cu lines in organic ultralow-k dielectric (Cu/Ta/ULK/SiCN) or silicon oxide dielectric (Cu/Ta/SiO₂/SiCN) and these results were compared with the results of the vacancy migration analyses. The number of SiV failures increased in the line with width of 0.35 μm for Cu/Ta/SiO ₂/SiCN interconnects and 0.20 μm for Cu/Ta/ULK/SiCN interconnects, respectively, under SiV acceleration tests. The results obtained by vacancy migration analysis show similar behavior as the results of SiV acceleration tests. These results reveal that the vacancy migration analysis is useful to predict reliability of interconnects.