Patent ID: 8461046

Claim:
A process, comprising: producing an insulating region on a lower metallization level; producing a hard mask on the insulating region defining the positions of vias through the insulating region and of metallic lines of an upper metallization level; etching the insulating region through the hard mask so as to form cavities, at least some of which open onto said lower metallization level; cleaning the cavities, where said cleaning forms an undercut at an interface between the hard mask and the insulating region; partially filling said cavities with copper along sidewalls of said cavities such that the partially filling copper is not formed on upper portions of the sidewalls of the cavities at the undercut and underside of the hard mask at the undercut; and sputtering a doped copper layer on the upper portions of the sidewalls of the cavities and underside of the hardmask so as to plug the undercut.