FABRICATION METHOD OF UBM BY ELECTROPLATING FOR FLIP CHIP INTERCONNECTIONS

摘要

PURPOSE: A fabrication method of UBM(under bump metallurgy) by electroplating for flip chip interconnections is provided to be capable of reducing fabrication cost and improving the reliability of the UBM. CONSTITUTION: A wafer having a predetermined pattern is dipped in a plating solution. At this time, the plating solution contains nickel ion supply source and copper ion supply source. The first copper layer(15) is formed at the upper portion of a pad(12) of a chip(11) by applying predetermined current density. A nickel-copper alloyed layer(16) is formed at the upper portion of the first copper layer as a diffusion barrier between a solder bump and the pad by increasing the current density. Preferably, the second copper layer(17) is formed at the upper portion of the nickel-copper alloyed layer by reducing the current density.