INTEGRATED PLASMA-PROMOTED CHEMICAL-VAPOR-DEPOSITION ROUTE TO ALUMINUM INTERCONNECT AND PLUG TECHNOLOGIES FOR EMERGING COMPUTER CHIP METALLIZATION

A low temperature plasma-promoted chemical vapor deposition (CVD) proc ess was developed for the formation of reliable aluminum interconnect and plug metallization schemes for applications in and beyond 0.25 mu m integrated chip device technology. The process employs aluminum sour ce precursors that are based on amine adducts of alane, such as dimeth ylethylamine alane, where the lack of a direct aluminum-carbon bond pr ovides a clean chemical pathway by which to eliminate the precursor's hydrocarbon groups at relatively low temperatures and yield pure alumi num films. The formation of dense and thick aluminum films at low temp erature and that have a smooth surface morphology is achieved by combi ning a radio-frequency hydrogen plasma at low power densities (below 0 .1 W/cm(2)) with a low frequency (<400 kHz) substrate bias. The use of a low power density plasma is designed to activate a uniform nucleati on of aluminum grains, thus eliminating the inherent problem of surfac e roughness that plagues thermal CVD processing, while avoiding undesi rable precursor gas phase decomposition and film contamination. Additi onally, the application of a substrate bias enhances the impingement r ate of precursor species on the substrate, and lead to an increase in the re-emission probability of such species inside via and trench stru ctures, leading to conformal step coverage and complete fill. The alum inum interconnect and plug structures produced were specular to thickn esses above 1 mu m, exhibited contamination levels below the 1 at. % d etection limit of x-ray photoelectron spectroscopy and Auger electron spectroscopy, and displayed postanneal resistivity of 3.38 mu Omega cm . Conformal fill of 0.25 mu m structures was achieved at growth rates in excess of 1000 Angstrom/min. (C) 1997 American Vacuum Society. [S07 34-211X(97)01505-9].