ELECTROPLATING OF Cu THROUGH ELECTRODES IN 3D PACKAGINGAuthors: N. Saito, R. Kiumi, and F. Kuriyama
Company: Precision Machinery Company, Ebara Corporation
Date Published: 11/3/2005 Conference: IWLPC (Wafer-Level Packaging)
The electroplating chemicals were composed of copper sulfate, sulfuric acid, hydrochloric acid and several kinds of additives of leveler, suppressor and accelerator. We found that the direct current plating was suitable for via filling, and electric current density was about 5mA/cm2 for higher aspect ratio via filling, and the chemicals could be flowed over a wafer surface uniformly by using the dip type of plating machine. The increasing of uniformity on over plated Cu film thickness could decrease polishing burden on removing Cu over-plating.
In our study, optimization was realized by adjusting plating conditions, and the nonuniformity of plated Cu film thickness was controlled being smaller to about 5-6% on a whole wafer, which was evaluated by means of the resistance meter Kokusai Electric VR-120. As a result, we fabricated the Cu through electrodes of diameter 5-50 µm, depth 35-150 µm, and aspect ratio 1.5-10. In this paper, we also discussed the effective factors and the fabrication processes on formation of Cu via filling in 3D packaging.
Key Words: via filling, through electrodes, electroplating, 3D packaging
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