Patent ID: 7718527

Claim:
A method of forming a semiconductor device, comprising: providing a patterned substrate containing a recessed feature formed in a low-k dielectric material and a first metallization layer at the bottom on the recessed feature; forming a first cobalt tungsten cap layer on the first metallization layer using a first cobalt precursor gas and a first tungsten precursor gas, wherein forming the first cobalt tungsten cap layer comprises forming alternating layers of cobalt metal and tungsten metal, alternating layers of cobalt metal and cobalt-rich cobalt tungsten, alternating layers of cobalt metal and tungsten-rich cobalt tungsten, alternating layers of tungsten metal and cobalt-rich cobalt tungsten, or alternating layers of tungsten metal and tungsten-rich cobalt tungsten; depositing a barrier layer in the recessed feature, including on the low-k dielectric material and on the first cobalt tungsten cap layer; and filling the recessed feature with copper (Cu) metal.