Patent ID: 7393781

Claim:
A method for forming a multilayer metal cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device comprising: depositing a first cobalt-based metal cap layer over the metal-filled interconnect feature in a first electroless deposition process employing a first electroless solution comprising a source of Co ions and a borane-based reducing agent and wherein the first metal cap layer is substantially continuous and has a thickness between about 5 angstroms and about 50 angstroms; and depositing a second cobalt-based metal cap layer over the first metal cap layer in a second electroless deposition process distinct from the first deposition process wherein the second deposition process is electroless and employs a second electroless solution which comprises a source of Co ions and a reducing agent, and which is distinct from, and prepared separately from, the first electroless solution, to thereby form the multilayer metal cap as a permanent component distinct from the metal-filled interconnect feature.