Co2Si

Co2Si is an intermetallic compound of cobalt and silicon with the stoichiometry Co2Si. It is one of several cobalt silicides that can form in the cobalt–silicon (Co–Si) binary system, depending on temperature and composition.

Formation and stability: Co2Si can be produced by high-temperature synthesis such as arc melting followed by annealing, or by diffusion processes during silicidation of cobalt films on silicon. In the Co–Si phase diagram, Co2Si is reported as a phase that may appear in certain temperature ranges, often alongside CoSi and CoSi2. Stability of Co2Si relative to other silicides depends on processing conditions and silicon activity.

Crystal structure and properties: Several reports describe Co2Si as an ordered intermetallic with a specific crystal structure; the precise lattice parameters vary by synthesis and study. Intermetallic cobalt silicides are typically hard, have high melting points, and exhibit metallic electrical conductivity. Some forms may be brittle.

Applications: In microelectronics, cobalt silicides are used for contacts and diffusion barriers; CoSi2 is the most established cobalt silicide for such uses. Co2Si has been studied in research settings for possible use in contacts or diffusion barriers, but it is not widely adopted in industry.

See also: cobalt silicides, CoSi, CoSi2, phase diagrams of cobalt and silicon.