Cobalt silcides thin films were prepared on Poly-Si/$SiO_2$/Si substrates by Co metal depostion using E-beam evaporation method and rapid thermal annealing for the application of inkjet printing heater. The crystal phases and composition distributions of the films were investigated as functions of the rapid thermal annealing (RTA) temperatures (600~$900^{circ}C$) and times (20~40 sec). The high temparature thermal stability was also investigated by the analysis of sheet resistance and crystalline properties. The stable $CoSi_2$ phases were obtained by the RTA annealing at $800^{circ}C$ for 20 seconds showing $0.8 Omega /Box$ of sheet resitance. However, the sheet resistances were sharply increased at below $700^{circ}C$ due to changes of crystalline phases. The temperature resistance coefficient of heating elements was found to be about $0.0014/^{circ}C$, and the obtained cobalt silicided films can be applied to the printer heating elements.