SIMS study of Cu trapping and migration in low-k dielectric films

Abstract A 545 nm thick low-k dielectric film was implanted at room temperature with 50 keV 63 Cu + to a dose of 1.0×1014 atoms/cm2. The film is a SiOx-based material and doped with about 8 at.% of flourine. Analyses by secondary-ion mass spectrometry show that Cu is fast diffuser in the low-k film, and after the RTA anneals Cu has redistributed within the film and some Cu has migrated to the interface between the low-k film and Si substrate. At 800 °C RTA, the apparent “diffusion” coefficient in the implanted film, DA, is estimated as ≈1.5×10−9 cm2/s. The 1100 °C RTA sample was re-analysed after stripping the low-k film and the result showed that 4.0×1012 atoms/cm2 Cu had moved into the silicon substrate to a depth of about 170 nm.