IMC study on Cu wirebond failures under high humidity conditions

Yamaji, Youhei; Hori, Masahiko; Ikenosako, Hirokazu; Oshima, Yumiko; Suda, Takao; Umeki, Akihiro; Kandori, Masayuki; Oida, Mitsuru; Goto, Hisaharu; Katsumata, Akio; Hiruta, Y.

doi:10.1109/eptc.2011.6184468

Cited by 13 publications

(10 citation statements)

References 4 publications

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“…Uno T [21] reported CuAl IMC interfacial corrosion under HAST environmental test. Yamaji Y et al [22] and Su P et al [23] reported similar CuAl IMC interfacial corrosion post HAST and UHAST tests and effects of pH of molding compounds on HAST failure rates. Lu YH et al [24] observed the growth rates of IMCs in Pd-coated Cu wire bonds are very sensitive to temperature, but the sequence of IMC formation remains the same for temperature below 350°C.…”

Section: Introductionmentioning

confidence: 77%

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Gan

Francis²,

Chan³

et al. 2014

Gold Bull

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This paper discusses the microstructure evolution of copper (Cu) and gold (Au) ball bonds after various extended reliability stresses such as biased highly accelerated temperature and humidity test (HAST), unbiased highly accelerated temperature and humidity test (UHAST), temperature cycling (TC), and high temperature storage life (HTSL) in BGA package. Objective of this study is to study the microstructure evolution and changes after long hours and long cycles of component reliability stressing and its predicted failure mechanisms and to determine the long-term reliability comparison with combination of bonding wires in HAST, UHAST, and TC. Secondary electron microscopy (SEM) and energy dispersive X-ray (EDX) have been carried out to understand the respective microstructure of failed samples in HAST, UHAST, TC, and HTSL long-term reliability failures. Respective failure mechanisms of copper and gold ball bonds carrion under HAST and UHAST, ball bond lifting in TC and HTSL have been analyzed and proposed. The evolution of surface morphology, including copper and gold ball bond micro cracking, gold ball bond Kirkendall microvoiding and intermetallic compound (IMC) formation, was studied in FBGA package with copper and gold ball bonds during various reliability stresses. Biased HAST, UHAST, TC, and HTSL mechanisms were proposed to explain the observed morphological changes and the resulting ball bond wear out modes after extended reliability stresses. Weibull reliability analyses have been established to compare the performance of copper and gold ball bonds under humid and dry environmental tests.

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Section: Introductionmentioning

confidence: 77%

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Gan

Francis²,

Chan³

et al. 2014

Gold Bull

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“…The identified cause for the observed Cu-Al IMC corrosion is the presence of halogen-ions at the bonding interface that migrate towards the bond pads driven by the positive bias and moisture absorption into the package during HAST [2,7]. With increasing halogen-ion concentration around the Cu-Al IMC contact, subsequent mechanisms are triggered as described previously.…”

Section: Imc Corrosion Mechanismmentioning

confidence: 90%

“…At zero hour during temperature enhanced ultrasonic compression bonding, a thin Cu-Al IMC layer is already formed. This layer will grow in vertical direction over time and different IMC phases will be formed: a thin film of Cu9Al4 IMC is observed close to the Cu ball; and a rugged CuAl2 IMC at Al bond pad side [2,6]. …”

Section: Cu-al Imc Growthmentioning

confidence: 99%

“…Figure 2 shows what such a failure physically looks like a lifted ball but is actually Cu-Al corrosion. This failure mode is not uncommon, usually as a result of poor bonding and attack by halogen-ions under high temperature/ high humidity / biased conditions, as has been discussed recently [2,3,4]. The key objective of this work is to study the influence factors and potential root causes of this failure mechanism.…”

Section: Introductionmentioning

confidence: 95%

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Cu wire HAST fail mechanism investigation for BGA package

Chang¹,

Huang²,

Pan³

2013

2013 8th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)

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The usage of copper wire is becoming more widespread in recent time. However, it is well known that copper wire is more critical compared to gold wire, in terms of wire bond workability and reliability. Especially, during HAST (Highly accelerated stress test) copper wire is sensitive for corrosion of the Cu-Al inter-metallic compound (IMC) resulting into ball lift failure. Therefore, the purpose of this paper is to study the root causes for HAST failures with copper wire bonding in BGA packages. Moreover, Cu-Al IMC corrosion is described with reference to recent publications. To increase product robustness against Cu-Al IMC corrosion, the factory environment and process control are important. In addition, the HAST test condition for the BGA packages specifically, is also proven to be an important parameter due to material stability. A combination of high halogen-ions concentration levels (e.g. Cl-) and bias will accelerate the Cu-Al IMC corrosion leading to ball lift failures.One potential source of halogen-ions is the substrate itself. Two different temperatures (110°C, 130°C) which are typical HAST test temperatures, were applied for the chemical analysis of the substrates. From test results, it was shown that extraction at higher temperature will lead to a higher concentration of halogen-ions. This increases the risk for Cu-Al IMC corrosion phenomena.In summary, it was revealed that halogen-ions from the substrate are released at higher HAST test temperature.

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“…The primary source of corrosion is the moisture content and the presence of halide element, Cl Ϫ content in packaging material (Uno, 2011;Boettcher et al, 2010;Yamaji et al, 2011;Tai et al, 2012;Zeng et al, 2013). As alluded to earlier, it is not an easy plug-and-play to switch from Au wirebonding to Cu wirebonding.…”

Section: Cu Wirebondingmentioning

confidence: 94%

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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IMC study on Cu wirebond failures under high humidity conditions

Cited by 13 publications

References 4 publications

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Cu wire HAST fail mechanism investigation for BGA package

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

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