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 CoSi 2 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 SiO x layer and annealing at 500–700° C led to the growth of essentially uniform, epitaxial CoSi 2 layers. The thin SiO x layer remained largely on the surface of the OME grown CoSi 2 layers as a cap. Deposition of cobalt at elevated temperature onto OME grown CoSi 2 layers led to a significant re-evaporation of cobalt from the SiO x surface. Presently, the OME effect was demonstrated on heavily doped p + and n + -Si and on narrow (0.22 µ m) Si lines. On all surfaces, thin (10–30nm), excellent quality, CoSi 2 single crystal thin films were grown by repeated growth sequences involving depositions of cobalt at room temperature and anneals at 600–700° C. It was also shown that faceting at CoSi 2 /Si(100) interfaces could be significantly reduced by a high temperature anneal.

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