A re-examination of the mechanism of thermosonic copper ball bonding on aluminium metallization pads
Silberschmidt, Vadim V.
Pramana, S. S.
White, Timothy John
Date of Issue2009
School of Materials Science and Engineering
The nanoscale interfacial characteristics of thermosonic copper ball bonding on aluminium metallization were investigated. It was found that ultrasonic vibration swept oxides of aluminium and copper from parts of the contact area, promoting the formation of intermetallic compound Al2Cu (approx.20 nm thick). Where oxides persisted, an amorphous aluminium oxide layer connected with a crystalline copper oxide. It was estimated that ultrasonic vibration caused an effective local temperature increase to 465 °C that accelerated interdiffusion and enhanced the formation of Cu–Al intermetallics.
© 2009 Acta Materialia Inc. This is the author created version of a work that has been peer reviewed and accepted for publication in Scripta Materialia, published by Elsevier on behalf of Acta Materialia Inc. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1016/j.scriptamat.2009.03.034].