Selective electroless plated nickel or cobalt plug contacts to n(+) and p(+) silicided junctions.

Step coverage of sputtered aluminum metallization presents a problem when the contact window aspect ratio (height/diameter) becomes greater than one. As a result, window plugs are of interest. Thick (0.5-1micron) selective electroless nickel or cobalt plating is used to provide "plug" contacts to CoSi (2) junctions. Details of the plating procedure are discussed. Contact resistance (single contact and via chain) and junction leakage data are presented for various hydrogen anneal cycles. It is concluded that aluminum/nickel plug metallization for silicide n(+)/p or p(+)/n junctions is promising when the final anneal temperature is below 400C. Above 400C, both aluminum- nickel and nickel-silicon interactions occur with nickel silicide resulting in failure of shallow (