Wearout reliability study of Cu and Au wires used in flash memory fine line BGA package

Gan, Chong Leong; Ng, EK; Chan, B. L.; Kwuanjai, T.; Jakarin, S.; Hashim, U.

doi:10.1109/impact.2012.6420213

Cited by 17 publications

(13 citation statements)

References 8 publications

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“…1 to 3 below. Cracking usually starts at the Cu ball bond periphery, and it will propagate toward the center of the Cu ball bond [9,10,13]. There is a possibility that under moist conditions, internal oxidation of intermetallic phases can result in oxidation of aluminum, precipitation of the noble metal (Au or Cu), and generation of hydrogen.…”

Section: Resultsmentioning

confidence: 99%

“…Zulkifli MN et al [7] suggested new approaches: examining the effect of individual phase and surroundings on the strengthening produced by the Au-Al intermetallic compound, combiningmore susceptible to moisture corrosion compared to gold ball bonds and undergoes different corrosion mechanisms in microelectronic packaging [11,12]. Our previous studies indicate that Pd-coated copper ball bond outperforms gold ball bonds in biased HAST wearout reliability [13]. Extended reliability of high-temperature storage life (HTSL) of copper ball bonds in TSOP package is found with apparent activation energy (E aa ) of~0.70 eV compared to gold ball bonds [14].…”

Section: Introductionmentioning

confidence: 99%

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Extended reliability of gold and copper ball bonds in microelectronic packaging

Gan

Francis²,

Chan³

et al. 2013

Gold Bull

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Wire bonding is the predominant mode of interconnection in microelectronic packaging. Gold wire bonding has been refined again and again to retain control of interconnect technology due to its ease of workability and years of reliability data. Copper (Cu) wire bonding is well known for its advantages such as cost-effectiveness and better electrical conductivity in microelectronic packaging. However, extended reliabilities of Cu wire bonding are still unknown as of now. Extended reliabilities of Au and Pd-coated Cu (Cu) ball bonds are useful technical information for Au and Cu wire deployment in microelectronic packaging. This paper discusses the influence of wire type and mold compound effect on the package reliability and after several component reliability stress tests. Failure analysis has been conducted to identify its associated failure mechanisms after the package conditions for Au and Cu ball bonds. Extended reliabilities of both wire types are investigated after unbiased HAST (UHAST), temperature cycling (TC), and high-temperature storage life test (HTSL) at 150, 175, and 200°C aging temperatures. Weibull plots have been plotted for each reliability stress. Obviously, Au ball bond is found with longer time to failure in unbiased HAST stress compared to Cu ball bonds for both mold compounds. Cu wire exhibits equivalent package and or better reliability margin compared to Au ball bonds in TC and HTSL tests. Failure mechanisms of UHAST and TC have been proposed, and its mean time to failure (t 50 ), characteristic life (t 63.2 , η), and shape parameter (ß) have been discussed in this paper. Feasibility of silver (Ag) wire bonding deployment in microelectronic packaging is discussed at the last section in this paper.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extended reliability of gold and copper ball bonds in microelectronic packaging

Gan

Francis²,

Chan³

et al. 2013

Gold Bull

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“…Key reliability challenges such silicon cratering with Cu ball bond; high humidity corrosion mechanism and ball bond shear per mil square have been laid out in our previous works (Gan et al, 2012b;2013a). Wearout failure mechanism of HAST and UHAST stress testing are caused by CuAl and AuAl IMCs interface corrosion and micro cracking and induced electrical ball bond opens (Gan et al, 2012d). The obtained values of E aa (in eV) of AuAl and CuAl IMC formation are 1.04 eV and 1.18 eV respectively.…”

Section: Ball Bond Wearout Reliabilitymentioning

confidence: 93%

“…The obtained values of E aa (in eV) of AuAl and CuAl IMC formation are 1.04 eV and 1.18 eV respectively. It clearly indicates that Au atoms diffuse at least five times faster than PdCu atoms in Al metallization of the 110 nm flash device tested (Gan et al, 2012d;. Au ball bonds show superior UHAST package reliability performance with higher mean-time-to failure hours (t 50 ) and characteristics life (t 63.2 ) in UHAST reliability plot (fitted to Weibull distribution) compared to Cu ball bond but not in TC stress regardless of the epoxy mold compound (EMC) effect.…”

Section: Ball Bond Wearout Reliabilitymentioning

confidence: 93%

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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“…Recently, copper wire bonding appears to be the alternate materials and various engineering studies on copper wire development have been reported [1]. Technical barriers and reliability challenges of Cu wire bonding in microelectronics packaging are well identified [2][3][4][5][6][7][8][9][10][11]. Au-Al microstructure evolution and intermetallic compound (IMC) formation is widely studied by Karpel et al [12].…”

Section: Introductionmentioning

confidence: 99%

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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Wearout reliability study of Cu and Au wires used in flash memory fine line BGA package

Cited by 17 publications

References 8 publications

Extended reliability of gold and copper ball bonds in microelectronic packaging

Extended reliability of gold and copper ball bonds in microelectronic packaging

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

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

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