METAL ALLOY LAYER OVER CONDUCTIVE REGION OF TRANSISTOR DEVICE OF DIFFERENT CONDUCTIVE MATERIAL THAN CONDUCTIVE REGION

A transistor device and method are disclosed for reducing parasitic resistance and enhancing channel mobility using a metal alloy layer over a conductive region. A transistor device may include a conductive region such as a source, drain and/or gate including at least one first conductive material, and a metal alloy layer disposed on substantially all of a surface of the conductive region, the metal alloy layer including a second conductive material different than the at least one first conductive materials. In one embodiment, the second conductive material includes a cobalt and/or nickel alloy. The metal alloy layer provides a non-epitaxial raised source/drain (and gate) to reduce the parasitic series resistance in, for example, nFETs fabricated on UTSOI. In addition, the metal alloy layer may include a stress to enhance mobility in a channel of the transistor device. The metal alloy layer may be formed using a selective electrochemical metal deposition process such as electroless or electrolytic plating.