Diffusion barrier enhancement for sub-micron aluminum-silicon contacts

Abstract

Methods for enhancing the effectiveness of barrier layers, needed to prevent interaction between overlying aluminum interconnect metallizations, and underlying silicon device regions, has been developed. One method consists of using dual layers of titanium nitride, on titanium disilicide. The first titanium nitride layer is obtained via rapid thermal annealing of an underlying titanium layer, in a nitrogen containing ambient, also resulting in the formation of the underlying titanium disilicide layer. The second titanium nitride layer is deposited using reactive sputtering. A second method, used to create an enhanced barrier layer, is to reactively sputter titanium nitride, directly on an underlying titanium layer. Rapid thermal annealing, in an ammonia and oxygen ambient, results in an oxygen containing titanium nitride barrier layer. The rapid thermal anneal cycle also converts the underlying titanium layer, to the desired titanium disilicide layer. The barriers produced by these methods have demonstrated barrier effectiveness, in terms of preventing aluminum penetration, when compared to counterparts, fabricated without the use of the processes, described in this invention.