We fabricated thermal evaporated 10 nm- (x=0.2, 0.5 and 0.8) /(poly)Si films to form nanothick cobalt nickel composite silicides by a rapid thermal annealing at for 40 seconds. A field emission scanning electron microscope and a micro-Raman spectrometer were employed for microstructure and silicon residual stress characterization, respectively. We observed self-aligned micro-pinholes on single crystal silicon substrates silicidized at . Raman silicon peak shift indicates that the residual tensile strain of in single crystal silicon substrates existed after the silicide process. We propose thermal stress from silicide exothermic reaction and high temperature silicidation annealing may cause the pinholes. Those pinholes are expected to be avoided by lowering the silicidation temperature. Our results imply that we may use our newly proposed composite silicides to induce the appropriate strained layer in silicion substrates.