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A micromechanism study of thermosonic gold wire bonding on aluminum pad

Lookup NU author(s): Dr Stevin PramanaORCiD

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Abstract

A micromechanism of thermosonic gold wire bonding was elaborated by examining its interfacial characteristics as a result of the bonding process, including the fragmentation of the native aluminum oxide layer on Al pads, and formation of initial intermetallic compounds (IMCs). It is found that the existence of an approximately 5 nm thick native oxide layer on original Al pads has a significant effect on the bonding, and the nucleation of IMCs during the bonding process must overcome this relatively inert thin film. Bonding strength was fundamentally determined by the degree of fragmentation of the oxide films, through which the formation of IMCs can be initiated due to the direct contact of the metal surfaces to be bonded. The extent of fracture the oxide layer was strongly influenced by the level of ultrasonic power, as at its high level alumina fragmentation becomes pervasive resulting in contiguous alloy interfaces and robust bonds. The IMCs formed at the interfaces were identified as Al 4 Al and AuAl2 with a thickness of 150-300 nm. The formation mechanism of such IMCs was explained by the effective heat of formation theory. © 2010 American Institute of Physics.

Publication metadata

Author(s): Xu H, Liu C, Silberschmidt VV, Pramana SS, White TJ, Chen Z, Sivakumar M, Acoff VL

Publication type: Article

Publication status: Published

Journal: Journal of Applied Physics

Year: 2010

Volume: 108

Issue: 11

Print publication date: 01/12/2010

ISSN (print): 0021-8979

ISSN (electronic): 1089-7550

Publisher: AIP Publishing

URL: https://doi.org/10.1063/1.3514005

DOI: 10.1063/1.3514005

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