Method and apparatus for simultaneously improving the electromigration reliability and resistance of damascene vias using a controlled diffusivity barrier

A method of creating a damascene interconnect for a semiconductor device having a first conductive line, a second conductive line, and a via electrically connecting the first and second conductive lines, the first conductive line having a device located at one end thereof, the method comprising the steps of:

• a) determining whether void formation at the device is of higher or of lower importance than void formation at the via;
• b) providing a diffusivity barrier layer having one of a first and second ability to prevent diffusion at an interface between the first conductive line and the via, wherein the first ability to prevent diffusion is greater than the second ability to prevent diffusion;
• and
• c) applying a reservoir of a first metal conductor at the one end of the first conductive line, the first metal conductor being of a same type as a second metal conductor disposed within the via and the first conductive line,
• wherein the reservoir of the first metal conductor provides metal atoms that are depleted from a region of the first conductive line adjacent to the device, the metal atoms acting as replacements for any metal atoms within the first metal conductor that have been moved in a direction away from the device, and
• wherein, if the determination in step a) is that void formation at the device is of higher importance than void formation at the via, the diffusivity barrier layer having the second amount of diffusivity is provided in step b), so that void formation at the device is minimized at the expense of void formation at the via, and
• wherein, if the determination in step a) is that void formation at the device is of lower importance than void formation at the via, the diffusivity barrier layer having the first amount of diffusivity is provided in step b), so that void formation at the via is minimized at the expense of void formation at the device.