NOVEL UNDER-BUMP METALLIZATION FOR BOND PAD SOLDERING

An under bump metallurgy (UBM) structure formed over a bond pad and for use in conjunction with a solder ball, provides an upper copper layer over a subjacent composite film that includes a nickel film over a further copper film over a titanium film. One or more reflow operations are used to form a...

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Bibliographische Detailangaben
Hauptverfasser:	CHEN CHIHIANG, TSAO PEI-HAW, WANG CHUNG Y, HUANG CHENDER, HUANG WEN S
Format:	Patent
Sprache:	eng
Schlagworte:	BASIC ELECTRIC ELEMENTS ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR ELECTRICITY SEMICONDUCTOR DEVICES
Online-Zugang:	Volltext bestellen
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Beschreibung
Zusammenfassung:	An under bump metallurgy (UBM) structure formed over a bond pad and for use in conjunction with a solder ball, provides an upper copper layer over a subjacent composite film that includes a nickel film over a further copper film over a titanium film. One or more reflow operations are used to form a molten solder ball and conditions are selected to ensure that all of the copper from the upper copper layer is dissolved within the molten solder. For SnAg leadfree solder, this leads to the formation of SnAgCu-like leadfree solder. The resulting interface between the solder ball and the nickel layer includes regularly spaced Cu6Sn5 nodules as intermetallics but is free of Ni3Sn4 which can spall into the molten solder causing reliability problems.