Electrodeposition of Indium for Low Temperature 3D Stacking

Extensive electrochemical analysis for Indium chloride electrolyte have been executed to make it applicable for fine pitch micro bump application. Indium micro bumps with under bump materials such as Copper, Nickel and Cobalt were fabricated in 20 μm pitch through-resist pattern. There was no defect at the interface between In and UBMs after deposition. The formation kinetics of intermetallic compounds and the interface reaction have also been investigated.