COBALT SELF-INITIATED ELECTROLESS VIA FILL FOR STACKED MEMORY CELLS

A method for electrolessly filling a stacked memory cell interconnect feature comprising electroless deposition from a composition comprising Co ions and a reducing agent by bottom-up filling initiated by reduction to Co metal on an electrically conducting bottom of the feature. An electroless deposition composition for electrolessly depositing Co in a high aspect ratio stacked memory cell interconnect feature, the composition comprising water, Co ions, a complexing agent, a buffering agent, a borane-based reducing agent component, and a hypophosphite reducing agent component. There is a concentration ratio of borane-based reducing agent to hypophosphite reducing agent of less than about 0.5.