Methods of forming niobium-near noble metal contact structures for

Abstract

Integrated circuit contact structures are fabricated by forming a first layer comprising niobium (Nb) on a silicon substrate and forming a second layer comprising a near noble metal on the first layer, opposite the silicon substrate. The near noble metal, also referred to as a Group VIII metal, is preferably cobalt (Co). The near noble metal has higher diffusion coefficient than the niobium and the silicon substrate. Annealing is then performed to diffuse at least some of the near noble metal through the first layer and react the diffused near noble metal with the silicon substrate to form a third layer comprising a near noble metal silicide, and to form a fourth layer comprising niobium-near noble metal alloy on the third layer. It has been found that the use of niobium can reduce substrate consumption compared to conventional cobalt titanium double-metal silicide fabrication processes. The annealing step is preferably performed in a nitrogen containing ambient to also form a fifth layer comprising niobium nitride on the fourth layer, opposite the third layer. Moreover, when a native oxide layer is included on the silicon substrate, the annealing step can react the niobium with the native oxide and thereby remove the native oxide layer.