The major aim of this study was to combine the techniques of using plasma immersion ion implantation (PIII) and electroless plating to implant Pd onto a Ta diffusion barrier layer as catalyst for the electroless Cu plating in order to accomplish the ULSI interconnection metallization. In our study, it has been demonstrated that the accelerating Pd+ ions by 2 kV pulsed negative bias voltages produce an amorphous Pd layer on β-Ta. The outermost Pd forms an oxide to the chemisorption of oxygen on Pd in air, while innermost Pd does not react with β-Ta, but instead remains in the form of metallic Pd. The Pd doses in the range of 5.7×1014 and 8.6×1014 cm−2 invokes an excellent catalytic effect on the electroless Cu plating. This results in an extraordinary ability for filling the submicron holes for gaining high quality electroless plated Cu interconnects, and thus qualifies for the traditional wet activation by SnCl2 and PdCl2 solutions.