Daniel J. Woodruff

Design of a Multiple-Electrode Magnetic-Alloy Plating Cell Using Numerical Modeling

Uniformity specifications for modern magnetic-alloy electroplating processes are stringent, and become more challenging as substrate sizes increase and product is driven closer to the substrate edge. Tight process specifications on uniformity and composition require electric field control and uniform electrolyte agitation. The latter is difficult because the substrate must maintain a fixed orientation with respect to a magnetic-field during processing. A new multiple-electrode, high-agitation cell for electroplating magnetic alloys is discussed. Mass-transfer simulations are used to design a multi-blade, oscillating structure that provides a spatially-uniform and controllable agitation level, which enables modification of alloy composition and/or deposition rate. Electric-field simulations are used to design a chamber in which the electric field can adapt to different electrochemical processes including various bath conductivities, substrate resistances, and applied currents. A remote placement of the thief electrode is used to avoid particle contamination on the substrate and to reduce thief maintenance.