The invention provides a method for forming a metal silicide layer. The method comprises steps of providing a substrate and forming a nickel-noble metal layer over the substrate. A grain boundary sealing layer is formed on the nickel-noble metal layer and then an oxygen diffusion barrier layer is formed on the grain boundary sealing layer. Thereafter, a rapid thermal process is performed to transform a portion of the nickel-noble metal layer into a metal silicide layer. Finally, the oxygen diffusion barrier layer, the grain boundary sealing layer and the rest portion of the nickel-noble metal layer are removed.
