The room-temperature electroless deposition of CoB film was investigated. Two reducing agents, sodium borohydride and dimethylaminoborane, were co-added to one bath to increase both the stability and reactivity of the solution. The proposed solution was used to form an in-situ capping layer during the buffing step in chemical mechanical polishing without an additional deposition process. A uniform and thin CoB film was formed during the capping process. The measurement of sheet resistance and Auger electron spectroscopy analysis on the surface revealed that it successfully prevented both the oxidation and diffusion of Cu resulting when exposed to air at 400 degrees C. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3600759] All rights reserved.