A fully integrated pillar process for high performance Cu interconnect scheme

A novel back-end of the line process for sub-quarter micron high performance devices, which is called the pillar process, has been proposed. The main features of the process is to form aluminum pillars as via plugs. Compared with the conventional metal plug process, the fine via opening process and complicated cleaning at the via interface are not required. By combining the pillar with a Cu single-damascene process, excellent electrical characteristics such as 20% lower wire resistance and 30% lower via resistance than that of conventional Cu dual-damascene structures have been obtained.