Patent ID: 7332193

Claim:
A method for electrolessly depositing a cobalt-based alloy selectively onto a metal-based substrate in manufacture of microelectronic devices, the method comprising: contacting the metal-based substrate with an electroless deposition composition to thereby electrolessly deposit the cobalt-based alloy selectively onto the metal-based substrate, wherein: the electroless deposition composition has a pH between about 7.5 and about 10; the electroless deposition composition comprises a) a source of cobalt deposition ions b) a source of hypophosphite for use as a reducing agent for reducing the depositions ions to metal onto the substrate, c) a hydrazine-based leveling agent present at a concentration to yield a hydrazine concentration in the electroless deposition composition from about 1 ppm to about 100 ppm; and d) a source of tungsten ions; and the cobalt-based alloy comprises cobalt metal, elemental phosphorus, and tungsten metal.