CVD AL FOR ADVANCED INTERCONNECT APPLICATIONS

A method for depositing low resistivity, high purity aluminum films by Chemical Vapor Deposition (CVD) is introduced. Pyrolysis of Dimethyl Aluminum Hydride (DMAH) using either H-2 or an inert gas as a carrier is shown to yield films with less than 0.01 at.% carbon and oxygen and resistivities of 3.0 mu Omega cm. The kinetics are exponentially temp erature dependent with E(act) similar to 0.5 eV independent of substra te. Introduction of some possible byproducts indicate that the deposit ion mechanism may be self reduction of DMAH. The morphology, wettabili ty, and step coverage of the films are shown to depend strongly on the nature of the substrate and how it is integrated with the CVD Al proc ess. Clustering of CVD Al with the deposition of the underlying liner is shown to be critical in achieving the highest quality films. Smooth , highly [111] oriented films with excellent reflectivity may be obtai ned. Some methods for Cu doping are discussed including a novel form o f in situ deposition. Complete via fill is obtained with blanket depos itions with one or two grains filling the vias in most cases. Vias as high as 3.5:1 aspect ratio are filled-sometimes with a single grain of Al. Electrical results indicate that the via resistances and electrom igration resistance of the Al plugs are excellent.