Effects of plasma surface treatment on the self-forming barrier process in porous sioch

Self-forming barrier process was carried out on a porous low-k material with the Cu-Mn alloys. The effects of various surface treatments were investigated in the sample having a pore size of 0.9 nm and a porosity of 25%. Before and after annealing, samples were analyzed in cross section with transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS). Concentration profile was also analyzed with time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The results indicated the penetration of Cu into the low-k interior during deposition, followed by the segregation of Cu at the low-k/Si interface during subsequent annealing. Although a diffusion barrier layer was formed and no further Cu penetration was not observed during annealing, initial Cu penetration in the deposition process was detrimental and should be prevented by restoring the plasma damage on the low-k surface.