Narrow (0.1μm - 0.5μm) copper lines for ultra-large scale integration (ULSI) Technology

Copper has been studied for Ultra-Large-Scale-Integration (ULSI) interconnect technology. A copper metalization system is proposed which includes both conducting and insulating barrier metals. Copper lines with minimum dimension of 100 nm were fabricated by electroless copper deposition. An alkaline-free deposition solution has been studied in addition to the conventional NaOH based solution. Two techniques have been developed to produce copper nanolines. The first method produced smooth non-planar copper lines with vertical sidewalls. Aspect ratios (height/width) as high as 3:1 have been obtained. The second fabrication technique formed a planar topography in which the copper is fully buried in an interlevel dielectric. Copper lines fabricated by both methods have been characterized by SEM. Problems unique to selective copper deposition are presented and discussed.