Fabrication of Nano Porous Gold towards Wafer Level Packaging

Conference: Smart Systems Integration - 13th International Conference & Exhibition on Integration Issues of Miniaturized Systems
04/10/2019 - 04/11/2019 at Barcelona, Spain

Proceedings: SmartSystems Integration

Pages: 8Language: englishTyp: PDF

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Hertel, Silvia; Jobke, Antje; Wiemer, Maik; Otto, Thomas (Fraunhofer ENAS, Technologie Campus 3, 09126 Chemnitz, Germany)
Reuter, Danny (TU Chemnitz, Center for Microtechnologies, Reichenhainer Str. 70, 09126 Chemnitz, Germany)

In this paper, the fabrication of nano porous gold (NPG) films by electrochemical dealloying is demonstrated. The NPG was formed from an electroplated gold-tin (Au-Sn) alloy from a commercial electrolyte on Si substrate. The electrochemical dealloying of Sn from Au-Sn alloy is a selective etching process, which is supported through an electrical potential. With this method, it is possible to fabricate NPG within 70 to 90 seconds for a 3 µm thick Au-Sn layer. In comparison, the chemical dealloying is reported with a duration of a few days. Within this work, the reproducibility of NPG fabrication and the adjustment of the porous structure is discussed. The stability of the used electrolyte allows the scaling to wafer level processes in future.