Ag Diffusion in Low-k Materials (BCN and SiOC) and Its Challenges for Future Interconnection

摘要

The diffusion of Ag and Cu in low-k films (BCN and SiOC) was investigated for future interconnections. From the depth profiles obtained by glow discharge optical emission spectroscopy (GDOES) after annealing, it was found that the rate of Ag diffusion in the BCN film was less than that in the SiOC film. It was also found that Cu diffused more easily in the SiOC film than in the BCN film. Current-voltage (Ⅰ-Ⅴ) characteristics were measured using a Ag or Cu electrode with and without annealing. The BCN film leakage current variation with and without annealing was less than that of the SiOC film. To improve RC delay time, Ag can be used because it has a lower resistivity than Cu; the BCN dielectric film can also be used because of its lower dielectric constant of 1.9 than that of the SiOC dielectric film.