BURIED COBALT SILICIDE LAYERS IN SILICON CREATED BY WAFER BONDING

A buried conductive layer in silicon has been created using wafer bond ing technique, with a cobalt interfacial layer. Co-coated silicon wafe rs were brought into contact with either similar or uncoated wafers at room temperature. CoSi2 was then formed through a solid-phase reactio n, during an anneal at 700 to 900-degrees-C. A 700 angstrom buried CoS i2-layer, with a resistivity of approximately 21 muOMEGA cm, was achie ved. Good adhesion, as measured by tensile strength testing, between t he wafers was achieved. Transmission electron microscopic investigatio ns (Co-coated wafer bonded to bare silicon) showed that the silicide h as not grown into the opposite wafer, and that an amorphous layer exis ts between the silicide and the silicon surface. The presence of such a layer has been confirmed by electrical characterization.