Intermetallic growth of wire-bond at 175°C high temperature aging

Chang, Hsihui; Pon, J. X.; Hsieh, Ker-Chang; Chen, C. C.

doi:10.1007/s11664-001-0146-4

Cited by 17 publications

(17 citation statements)

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“…10 In that study, the degradation was started at the interface between gold and the gold-aluminum intermetallic phases. Figure 1, the whole microstructure, shows the wire-bond microstructure attacked by Br at 175°C.…”

Section: Resultsmentioning

confidence: 99%

Bromine- and chlorine-induced degradation of gold-aluminum bonds

Lue

Huang

et al. 2004

Journal of Elec Materi

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The presence of bromine (Br) in flame retardant epoxies accelerates the degradation of gold-aluminum wire bonds. This experiment tests degradation by adding 5 wt.% 2,6-dibromophenol to the regular molding compound and holding thermal aging at 175°C and 205°C in ovens for up to 1,008 h. The intermetallic degrading microstructure was examined at different aging times. In order to better understand the mechanism behind the degradation, bulk Au 4 Al and Au 5 Al 2 single-intermetallic phases were prepared and reacted with molding compound at 205°C. The reactions were analyzed by a JEOL (Japan Electron Optics Ltd., Tokyo) Superprobe JXA-8900R under wavelength-dispersive spectrometry of x-ray mode. A similar chloride degrading study was performed by adding Tetrachlorobisphenol A to the regular molding compound. The results show that Br attacked the Au 4 Al phase first and then the Au 5 Al 2 phase. The chloride reacted with the Au 4 Al phase only.

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Section: Resultsmentioning

confidence: 99%

Bromine- and chlorine-induced degradation of gold-aluminum bonds

Lue

Huang

et al. 2004

Journal of Elec Materi

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“…However, this bonding system can easily lead to formation of Au-Al intermetallic compounds (IMCs). [1][2][3][4][5][6] Such IMCs are associated with Kirkendall voids, detrimentally affecting the reliability of components, especially in high-power devices and fine-pitch electronic applications. The use of Cu wire for thermosonic ball bonding presents several advantages over the use of Au wire, including significant cost saving, higher electrical and thermal conductivity for faster die functionality, and better mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Growth of Intermetallic Compounds in Thermosonic Copper Wire Bonding on Aluminum Metallization

Liu

Silberschmidt

et al. 2009

Journal of Elec Materi

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Interface evolution caused by thermal aging under different temperatures and durations was investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that approximately 30-nm-thick and discontinuous Cu-Al intermetallic compounds (IMCs) were present in the initial bonds before aging. Cu-Al IMCs grew under thermal aging with increasing aging time. The growth kinetics of the Cu-Al IMCs was correlated to the diffusion process during aging; their combined activation energy was estimated to be 1.01 eV. Initially, Al-rich Cu-Al IMCs formed in the as-bonded state and early stage of aging treatment. Cu 9 Al 4 was identified by selected-area electron diffraction (SAD) as the only type of Cu-Al IMC present after thermal aging at 250°C for 100 h; this is attributed to the relatively short supply of aluminum to the interfacial reaction.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] According to a phase diagram in the binary Au-Al system, 14) six compounds appear as stable phases at temperatures lower than 773 K. They are Au 4 Al, Au 5 Al 2 , -Au 2 Al, -Au 2 Al, AuAl and AuAl 2 . In a recent supplement of the phase diagram, 15) however, Au 5 Al 2 is replaced by Au 8 Al 3 .…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the stoichiometry Au 8 Al 3 is adopted in the present article. An experiment of the reactive diffusion was conducted by Chang et al 8) using diffusion couples composed of a Au wire and a thin Al layer. In this experiment, the diffusion couple was isothermally annealed at 448 K for various times up to 1008 h. During annealing, Au 2 Al, Au 8 Al 3 and Au 4 Al are formed at the initial Au/Al interface in the diffusion couple.…”

Section: Introductionmentioning

confidence: 99%

“…Similar results were reported also by Noolu et al 10) and Breach and Wulff. 11) Since the initial thickness of the Al layer in the diffusion couple is small, 8) however, soft impingement of diffusion may occur in the Au layer after a certain annealing time and will influence the growth behavior of the compound. Furthermore, in the late stages, the Al layer is completely consumed by the growth of the compound.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Solid-State Reactive Diffusion between Au and Al

Minho

Kajihara

2011

Mater. Trans.

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In the wire bonding technique, a thin Au wire is interconnected with an Al layer on a Si chip. During energization heating at solid-state temperatures, however, brittle Au-Al compounds with high electrical resistivities are formed at the interconnection by the reactive diffusion between Au and Al. In order to examine the growth behavior of the Au-Al compounds, the kinetics of the reactive diffusion was experimentally observed using sandwich Al/Au/Al diffusion couples. The diffusion couple was prepared by a diffusion bonding technique and then isothermally annealed at temperatures of 623-723 K for various times up to 103 h. Under such annealing conditions, the diffusion couple is practically considered semi-infinite. Owing to annealing, compound layers consisting of AuAl 2 , AuAl and Au 8 Al 3 are produced at the initial Au/Al interface in the diffusion couple. The volume fraction in the compound layers is larger for Au 8 Al 3 than for AuAl and AuAl 2 in the early stages but becomes smaller for Au 8 Al 3 than for AuAl and AuAl 2 in the late stages. However, there are no systematic dependencies of the volume fraction on the annealing time and temperature. The total thickness of the compound layers is proportional to a power function of the annealing time. The exponent of the power function is smaller than 0.5 at 673-723 K. The exponent smaller than 0.5 means that the interdiffusion across the compound layers governs the layer growth and boundary diffusion predominantly contributes to the interdiffusion. On the other hand, at 623 K, the exponent is equal to unity for annealing times shorter than 8 h but smaller than 0.5 for those longer than 8 h. The exponent of unity indicates that the layer growth is controlled by the interface reaction at the migrating interface. Thus, at T ¼ 623 K, the transition of the ratecontrolling process occurs at a critical annealing time of 8 h.

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Intermetallic growth of wire-bond at 175°C high temperature aging

Cited by 17 publications

References 3 publications

Bromine- and chlorine-induced degradation of gold-aluminum bonds

Bromine- and chlorine-induced degradation of gold-aluminum bonds

Growth of Intermetallic Compounds in Thermosonic Copper Wire Bonding on Aluminum Metallization

Kinetics of Solid-State Reactive Diffusion between Au and Al

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