Diffusion Boundary Layer Studies in an Industrial Wafer Plating Cell

Abstract

Linear sweep voltammetry and chronoamperometry methods were used to measure limiting current in an industrial wafer-plating cell. Copper deposition in a dilute solution, under mass-transfer-limited conditions, is used to study the variation of the mass transfer boundary-layer thickness. It is shown that a shear-plate fluid agitation mechanism is capable of generating a thin (i.e., ), spatially uniform and nonperiodic boundary layer across the entire wafer. It is anticipated that thin boundary layer deposition will prove to be beneficial in MEMS, flip-chip bumping, and WL-CSP applications.