Intermetallic phase transformations in Au-Al wire bonds

H. Xu; C. Liu; V. V. Silberschmidt; S. S. Pramana; T. J. White; Z. Chen; V. L. Acoff

doi:10.1016/j.intermet.2011.07.003

Intermetallic phase transformations in Au-Al wire bonds

H. Xu^*, C. Liu, V. V. Silberschmidt, S. S. Pramana, T. J. White, Z. Chen, V. L. Acoff

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

52 Citations (Scopus)

Abstract

This paper describes the crystallochemical mechanisms that underpin the migration of nano-size alumina, intermetallic growth and phase transformations in Au-Al wire bonds during annealing from 175 °C to 250 °C by utilizing high-resolution transmission electron microscopy (HRTEM). Alumina, encapsulated within the Au-Al intermetallic compounds (IMCs), migrates towards the Au ball during annealing, with Au diffusion into the Al pad. The sequence of Au-Al IMC phase development during annealing was investigated. Initially, Au ₈Al₃ appears as a third phase between the Au₄Al and AuAl₂ layers that form during bonding, and gradually becomes the dominant compound. Both AuAl₂ and Au₈Al₃ are transformed into the Au-rich alloyAu₄Al when Al is completely consumed, and this is the terminal product.

Original language	English
Pages (from-to)	1808-1816
Number of pages	9
Journal	Intermetallics
Volume	19
Issue number	12
DOIs	https://doi.org/10.1016/j.intermet.2011.07.003
Publication status	Published - Dec 2011
Externally published	Yes

ASJC Scopus Subject Areas

General Chemistry
Mechanics of Materials
Mechanical Engineering
Metals and Alloys
Materials Chemistry

Keywords

A. Aluminides
B. Phase transformation
C. Wire bonding
D. Microstructure
F. Electron microscopy

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10.1016/j.intermet.2011.07.003

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title = "Intermetallic phase transformations in Au-Al wire bonds",

abstract = "This paper describes the crystallochemical mechanisms that underpin the migration of nano-size alumina, intermetallic growth and phase transformations in Au-Al wire bonds during annealing from 175 °C to 250 °C by utilizing high-resolution transmission electron microscopy (HRTEM). Alumina, encapsulated within the Au-Al intermetallic compounds (IMCs), migrates towards the Au ball during annealing, with Au diffusion into the Al pad. The sequence of Au-Al IMC phase development during annealing was investigated. Initially, Au 8Al3 appears as a third phase between the Au4Al and AuAl2 layers that form during bonding, and gradually becomes the dominant compound. Both AuAl2 and Au8Al3 are transformed into the Au-rich alloyAu4Al when Al is completely consumed, and this is the terminal product.",

keywords = "A. Aluminides, B. Phase transformation, C. Wire bonding, D. Microstructure, F. Electron microscopy",

author = "H. Xu and C. Liu and Silberschmidt, {V. V.} and Pramana, {S. S.} and White, {T. J.} and Z. Chen and Acoff, {V. L.}",

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AU - Xu, H.

AU - Liu, C.

AU - Silberschmidt, V. V.

AU - Pramana, S. S.

AU - White, T. J.

AU - Chen, Z.

AU - Acoff, V. L.

PY - 2011/12

Y1 - 2011/12

N2 - This paper describes the crystallochemical mechanisms that underpin the migration of nano-size alumina, intermetallic growth and phase transformations in Au-Al wire bonds during annealing from 175 °C to 250 °C by utilizing high-resolution transmission electron microscopy (HRTEM). Alumina, encapsulated within the Au-Al intermetallic compounds (IMCs), migrates towards the Au ball during annealing, with Au diffusion into the Al pad. The sequence of Au-Al IMC phase development during annealing was investigated. Initially, Au 8Al3 appears as a third phase between the Au4Al and AuAl2 layers that form during bonding, and gradually becomes the dominant compound. Both AuAl2 and Au8Al3 are transformed into the Au-rich alloyAu4Al when Al is completely consumed, and this is the terminal product.

AB - This paper describes the crystallochemical mechanisms that underpin the migration of nano-size alumina, intermetallic growth and phase transformations in Au-Al wire bonds during annealing from 175 °C to 250 °C by utilizing high-resolution transmission electron microscopy (HRTEM). Alumina, encapsulated within the Au-Al intermetallic compounds (IMCs), migrates towards the Au ball during annealing, with Au diffusion into the Al pad. The sequence of Au-Al IMC phase development during annealing was investigated. Initially, Au 8Al3 appears as a third phase between the Au4Al and AuAl2 layers that form during bonding, and gradually becomes the dominant compound. Both AuAl2 and Au8Al3 are transformed into the Au-rich alloyAu4Al when Al is completely consumed, and this is the terminal product.

KW - A. Aluminides

KW - B. Phase transformation

KW - C. Wire bonding

KW - D. Microstructure

KW - F. Electron microscopy

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DO - 10.1016/j.intermet.2011.07.003

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JO - Intermetallics

JF - Intermetallics

IS - 12

ER -

Intermetallic phase transformations in Au-Al wire bonds

Abstract

ASJC Scopus Subject Areas

Keywords

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