@INPROCEEDINGS{Eacock2014,
  author = {Florian Eacock AND Mirko Schaper AND Simon Althoff AND Andreas Unger
	AND Paul Eichwald AND Florian Hengsbach AND Carolin Zinn AND Martin
	Joachim Holzweissig AND Karsten Guth},
  title = {Microstructural investigations of aluminum and copper wire bonds},
  booktitle = {Proceedings of the 47th International Symposium on Microelectronics},
  year = {2014},
  abstract = {Nowadays wire bonding is a widely-used technology for interconnecting
	chips in the packaging industry. Thereby, it is known that the bond
	quality massively depends upon the microstructure prevailing in the
	bond and consequently the materials used as well as the bonding parameters.
	However the actually used materials such as aluminum and gold are
	either characterized by comparibly poor conductivity or high costs,
	respectively. Due to its outstanding properties copper is a more
	attractive candidate. Still, a thorough investigation on the interrelationship
	between the material combinations, the processing parameters and
	the resulting microstructure for copper and aluminum wire bonding
	was not carried out yet. Depending on the aforementioned factors
	the microstructural evolution can be completely different during
	the bonding process. Therefore, this study focuses on the microstructural
	evolution of heavy copper and heavy aluminum wires bonded on copper
	substrates. The evolution of the wire microstructure as well as the
	wire-substrate-interface was investigated by scanning electron microscope
	in combination with electron backscatter diffraction and microhardness
	measurements. Various samples were extracted at different points
	of the bonding process, namely the as-received condition, after touchdown
	and after completed bonding. The results of the aluminum and copper
	wires were compared to each other in both longitudinal and transversal
	direction. It was found, that the two wire materials were completely
	different in the as-received condition regarding the grain size,
	the grain morphology, the texture and the microhardness. After touchdown
	the microstructure did not show significant changes in both materials,
	yet a strain-hardening was observed in the copper wire resulting
	from the touchdown force. When the bonding process was completed
	a different microstructure could be observed in both the wire as
	well as the layer for the materials investigated. Furthermore, a
	destinctive increase in the wire hardness could be found in case
	of copper, which was not observed for the aluminum wire. The ramifications
	between the two wire materials presented in this work will be discussed
	with the objective of optimizing the quality of the bonds.},
  doi = {10.4071/isom-THP32},
  file = {Eacock2014.pdf:Eacock2014.pdf:PDF},
  keywords = {Bonding, Copper, Microstructure evolution},
  owner = {tobiasm},
  timestamp = {2014.11.10}
}