Intermittent electroless nickel deposition in a fine trench flip chip bumppad

An intermittent electroless nickel deposition process was examined which in volved periodically removing and reinserting the silicon wafer in the depos ition bath. this process results in electroless nickel deposits with a smoo th surface appearance and uniform thickness within the bump opening. The in termittent deposition process also results in enhancement in deposition spe ed. The benefits of this process are ascribed to replenishment of the surfa ce concentration and the breakdown of entrapped gas bubble in the trench ar ea of bump pad. (C) 2000 The Electrochemical Society.