Challenges and developments of copper wire bonding technology

Liu, Peisheng; Tong, Liangyu; Wang, Jinlan; Shi, Lei; Tang, Hao

doi:10.1016/j.microrel.2011.12.013

Cited by 71 publications

(32 citation statements)

References 48 publications

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“…Hence, in-depth first ball bonding should be characterized to minimize underneath silicon cratering phenomenon with Cu wirebonding. Key Cu wirebonding process developments and ongoing reliability monitoring have been laid out extensively to address those technical barriers to replace Au wirebonding in semiconductor packaging (Appelt et al, 2011;Zhong, 2009;Chauhan et al, 2013;Liu et al, 2012). Hiew et al (2012) disclosed detailed study on the challenges of development of a robust Cu wire bond process on thin Al bond pad (0.8-m thick) to meet Automotive Electronics Council Grade 1 (AECG1) requirements.…”

Section: Cu Wirebondingmentioning

confidence: 99%

Future and technical considerations of gold wirebonding in semiconductor packaging – a technical review

Gan¹,

Francis²,

Chan

et al. 2014

Microelectronics International

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Purpose -The purpose of this paper is to provide a systematic review on technical findings and discuss the feasibility and future of gold (Au) wirebonding in microelectronics packaging. It also aims to study and compare the cost, quality and wear-out reliability performance of Au wirebonding with respect to other wire alloys such as copper (Cu) and silver (Ag) wirebonding. This paper discusses the influence of wire type on the long-term reliability tests. Design/methodology/approach -Literature reviews are conducted based on cost and wire selections of Au, Cu or Ag wirebonding. Detailed wear-out failure findings and wire selection with cost considerations are presented in this review paper. The future and the status of Au wirebonding in microelectronics packaging are discussed in this paper. Findings -This paper briefly reviews selected aspects of the Au ball and other alternative bonding options, focusing on reliability performance, and discusses the future of Au wirebonding in the near future in semiconductor packaging. Practical implications -The paper reveals the technical considerations when choosing the wire types for future microelectronics packaging. Originality/value -The in-depth technical review and strategies of the selection of wire types (Au, Cu or the latest Ag alloy) in microelectronics packaging are discussed in this paper based on previous literature studies.

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Section: Cu Wirebondingmentioning

confidence: 99%

Future and technical considerations of gold wirebonding in semiconductor packaging – a technical review

Gan¹,

Francis²,

Chan

et al. 2014

Microelectronics International

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“…But copper wire is easy oxidized, and Cu/Al intermetallics compounds easy form voids in high-humidity and high-temperature environment, so the copper bonding wire is limited in larger scale integrated circuit and LED field. Silver alloy is un-active, and has lower resistance and good anti-oxidation performance, so silver alloy bonding wire was used in LED microelectronic packaging industry [1][2][3][4][5][6][7] . Recently, bonding pad (metallization) materials have been changed from Al to noble metals, such as Pd and Au to improve light emission efficiency in LED devices, to simplify the metallization process in Cu/Low-k wafers, to obtain higher bonding reliability (no intermetallics, no voids), and to reduce the electrical noise in radio frequency devices [8][9][10][11][12] .…”

Section: ⅰ Introductionmentioning

confidence: 99%

Effect of Ag-4Pd alloy bonding wire properties and structure on bond strengths and reliability

Cao¹,

Fan²,

Gao³

2016

2016 International Conference on Electronics Packaging (ICEP)

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Abstract：The different of Ag-4Pd and Ag-4Pd-0.3Ru alloy bonding wire properties and structure were analyzed by scanning electron microscope, strength tester and thermal conductivity tester, the effects of Ru on Ag-4Pd alloy bonding wire ball size, bonded micro phonology and bonded strength were investigated. The results show that the thermal conductivity of Ag-4Pd alloy bonding wire decreases from 403 W/m•k to 365 W/m•k because of doping Ru, and the free air ball shape of Ag-4Pd-0.3Ru alloy bonding is more uniform than Ag-4Pd alloy bonding wire, the Ag-4Pd-0.3Ru alloy bonding wire bonded strength is higher than AgA1 alloy bonding wire. The heat affect zone length decreases from 50μm to 35μm because of doping Ru, and the ball neck crack defect cause of excessive long heat affect zone length will decrease. For Ag-4Pd alloy bonding wire, Ru can refine the grain, then the grain size decreases, and the grain quantity increases, then the inhomogeneous deformation of different grain decrease, and the ball bonded shape is uniform. After HTS test, cracks phenomenon happens at the bonding interface because of Ag atoms rapidly migrate, Zn can decrease the Ag migrate rate and avoid the crack in bonded interface.

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“…Since Au is expensive and Al is not strong enough, copper (Cu) wire has recently been adapted. A major challenge for Cu wire is oxidation, making it difficult to bond to interconnect pads [11][12][13]. A great deal of research has been conducted to deal with Cu oxidation by coating Cu wires with noble metal such as palladium (Pd), Au, and Ag [14,15].…”

Section: Introductionmentioning

confidence: 99%

A solid-state bonding technique of large copper wires for high power devices operating at high temperature

Lee

2015

J Mater Sci: Mater Electron

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Solid-state processes of bonding 1 mm copper (Cu) wires on Cu substrates and silicon (Si) chips, respectively, were developed. To overcome Cu oxidation issue, the bonding surface on the wire was plated a silver (Ag) layer. An annealing step followed to make the Ag layer much easier to deform and conform to the Cu or Si bonding surfaces. The bonding process was performed at 300°C with 6.89 MPa. Wire-bond cross sections were studied using optical and electron microscopy, respectively. The images obtained exhibit nearly perfect Ag-Cu bonding interface. For wire-bonds made on Cu substrate, in-plane (shear) pull test measured a breaking of force 20.7-23.7 kg, comparable to the 22.5 kg breaking force of the Cu wire itself. Breaking forces on vertical (peel) pull test are about one-half of in-plane pull test results. For wire-bonds made on Si chip, breaking forces are about 80 % of those made on Cu substrate. Fracture modes were evaluated in details. 90 % of the wire-bonds broke with three modes mixed together: near Cu-Ag plating interface, inside Ag layer, and Ag-Cu bonding interface. Thus, the bonding interface is as strong as other regions of the wirebond. This solid-state wire bonding process is expected to have valuable applications in high power and high temperature devices and modules where the wire-bonds have to stand alone without protection due to lack of high temperature molding compound and reinforcing materials.

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Challenges and developments of copper wire bonding technology

Cited by 71 publications

References 48 publications

Future and technical considerations of gold wirebonding in semiconductor packaging – a technical review

Future and technical considerations of gold wirebonding in semiconductor packaging – a technical review

Effect of Ag-4Pd alloy bonding wire properties and structure on bond strengths and reliability

A solid-state bonding technique of large copper wires for high power devices operating at high temperature

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