New observation of nanoscale interfacial evolution in micro Cu–Al wire bonds by in-situ high resolution TEM study

Three types of interfacial nanostructure are identified in as-bonded Cu–Al bonds: (1) Cu/~5nm amorphous alumina layer/Al; (2) Cu/~20nm CuAl2 intermetallic particle/Al; and (3) Cu/Al. During annealing, in the areas of latter two types where alumina layer is fragmented, Cu9Al4 and CuAl form as second...

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Bibliographic Details
Published in:Scripta materialia 2016-04, Vol.115, p.1-5
Main Authors: Xu, Hui, Qin, Ivy, Clauberg, Horst, Chylak, Bob, Acoff, Viola L.
Format: Article
Language:English
Subjects:
Aluminum
ALUMINUM OXIDE
ANNEALING PROCESSES
BONDS
Copper
Copper–aluminum
DIFFUSION
Diffusion layers
Diffusion rate
In-situ TEM
INTERFACES
Interfacial structure
Intermetallic compounds
Intermetallics
MICROSTRUCTURES
Nanostructure
WIRE
Wire bond
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Summary:Three types of interfacial nanostructure are identified in as-bonded Cu–Al bonds: (1) Cu/~5nm amorphous alumina layer/Al; (2) Cu/~20nm CuAl2 intermetallic particle/Al; and (3) Cu/Al. During annealing, in the areas of latter two types where alumina layer is fragmented, Cu9Al4 and CuAl form as second and third intermetallic layers, and grow vertically and fast together with initial CuAl2. In the area of first type where alumina layer is present, CuAl2 grows laterally and slowly via Cu diffusion through intermetallic compounds in the neighboring area where alumina is broken to reach Al. Cu–Al interdiffusion is dominated by Cu diffusion. [Display omitted]
ISSN:1359-6462
1872-8456
DOI:10.1016/j.scriptamat.2015.12.025