A novel technique for ultrathin CoSi2 layers: Oxide mediated epitaxy

A novel technique, oxide mediated epitaxy (OME), was recently described for the growth of single crystal CoSi2 layers on the (100), (110); and (111) surfaces of silicon. Deposition of a thin layer of cobalt (1-3 nm) onto Si surfaces covered with a thin peroxide-grown SiOx layer and annealing at 500-700 degrees C led to the growth of essentially uniform, epitaxial CoSix layers. The thin SiOx layer remained largely on the surface of the OME grown CoSi2 layers as a cap. Deposition of cobalt at elevated temperature onto OME grown CoSi2 layers led to a significant re-evaporation of cobalt from the SiOx surface. Presently, the OME effect was demonstrated on heavily doped p(+) and n(+)-Si and on narrow (0.22 mu m) Si lines. On all surfaces, thin (10-30nm), excellent quality CoSi2 single crystal thin films were grown by repeated growth sequences involving depositions of cobalt at room temperature and anneals at 600-700 degrees C. It was also shown that faceting at CoSi2/Si(100) interfaces could be significantly reduced by a high temperature anneal.