Characterization of the Co film deposited by MOCVD using dicobalt (Hexacarbonyl) tert-butylacetylene and the CoSi2 film formed by a two-step annealing process with a Ti capping layer

Abstract

We investigated the effects of a Ti capping layer on the formation of a CoSi2 film by using a two-step annealing process. The Co films were deposited by a metal-organic chemical vapor deposition (MOCVD) method using dicobalt hexcarbonyl tert-butylacetylene (C12H10O6(Co)(2), CCTBA) as the Co precursor with H-2 reactant gas under optimized process condition. Then a Ti capping layer was deposited on the Co film by electron beam evaporation. The Ti capping layer captures oxygen which is present in the interface and film, and protects the silicide from oxygen contamination during Co silicidation. The Ti capping layer also affected the formation of smooth and uniform CoSi2 films during the silicide reaction. The two-step annealing process was chosen to form the CoSi2 phase. After the first annealing process for forming the Co2Si or CoSi phases, a selective etching was utilized to remove any remaining metal such as unreacted Co and the Ti capping layer. A second annealing process was finally performed to transform from the highly resistive CoSi to the low resistive CoSi2.