Comparison of κ<3 silicon oxide-based dielectric pre-copper metallization preclean processes using black diamond

Low dielectric constant silicon oxide-based films which incorporate a high density of nanometersized pores are receiving widespread attention because of a combination of compelling attributes. Plasma processes which are used to clean copper pads at the bottom of vias prior to copper diffusion barrier film deposition are examined with respect to their effect on a PECVD low density silicon-oxide-based low-κ film. Reactive preclean using 5%H₂/95%He is best for these low-κ silicon oxide-based films, for both plasma overashed films (resulting from photoresist removal) and unashed films, compared to sputter precleaning and reactive precleaning using 10%H₂/90%He. Lower reactive preclean coil power and shorter preclean times result in the lowest increase in dielectric constant