High temperature characteristics of new metal core rod and diffusion barrier materials for polysilicon production

Abstract

The refractory metal and their alloys were investigated to replace the Si core rod in bell-jar reactor for poly-Si production. And diffusion barrier materials for block the infiltration of impurities at high temperature were studied. The various thin films were deposited on Si wafer by co-sputtering system and heat-treatments were carried out in electrical tube furnace with a double column. To evaluate the characteristics of prepared films, SEM(Scanning Electron Microscope), XRD(X-Ray Diffractometer), AES(Auger Electron Spectroscope) and FE-TEM(Transmission Electron Microscope) were employed. W/Si, Ta-Mo/Si, W-Ta-Mo/Si and W-Mo/Si films were prepared by co-sputtering system. As a result of experiments, tantalum has a high oxidation property, so it was excluded from candidate of core rod materials. And W-Mo alloy contained molybdenum of 40% shows the good properties as a core rod material. The quaternary nitride films of W-Si-B-N barrier materials were studied for development of diffusion barrier. To observe the $N_2$ and B effect, W-Si-B-N films were prepared with varying the $N_2$ partial pressure and B/$WSi_2$ ratio. W-Si-B-N/Si film which is deposited under conditions of 0.5 $N_2$ partial pressure and 1 B/$WSi_2$ sputter power ratio was shown the best performance as a diffusion barrier.