Fabrication of Gold Bumps Using Gold Sulfite Plating

Abstract

Fabrication of small gold bumps ( in size) on silicon substrates were investigated using gold sulfite plating. To improve the stability of the gold sulfite plating bath, the behavior of the decomposition procedures and evaluation of the stabilizer were also studied. It was confirmed that Au metal and Au3+ ions were produced in the decomposed plating solution. The most effective stabilizer was 2,2'‐bipyridine. This greatly improved the stability of the bath. The gold sulfite electrolyte did not attack the photoresist, and straight‐walled bumps with 20 μm in pitch and 20 μm in height can be obtained.