Embodiments of the present invention generally provides compositions of the plating solution, a method of depositing a capping layer on the method and the plating solution is mixed with the plating solution. Plating solutions described herein, it can be used as the electroless deposition solution to deposit a capping layer on the conductive features on. The plating solution is a dilute solution rather, contains a strong reducing agent to self initiate a conductive feature on. Plating solution may be provided in-situ cleaning process for the conductive layer while depositing a capping layer containing no particles. In one embodiment, buffered comprising deionized water, adjusting buffer solution containing a first complexing agent, a cobalt-containing solution containing cobalt source and a second complexing agent, a hypophosphorous acid salt source and the borane reducing agent a method for forming an electroless deposition solution that involves combining a reduction solution is provided.
.FIELD 6