Corrosion study at Cu–Al interface in microelectronics packaging

Tan, C.W.; Daud, Abdul Razak; Yarmo, Mohd Ambar

doi:10.1016/s0169-4332(02)00150-2

Cited by 92 publications

(43 citation statements)

References 8 publications

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“…During the period from 1995 to 2002, there were few studies of note on copper, except for Tan et al [26] in 2002, which described silicon cratering as '..a major hurdle to overcome..' and like previous studies concluded Pull strength (grams force) 8 22 that higher ultrasound needed to soften copper balls causes more cratering and that harder bond pads could help in eliminating cratering. Tan described PCT experiments on un-moulded copper ball bonds [27] bonded at 350°C and observed high shear forces with time and a drastic reduction of shear force due to corrosion and formation of copper and aluminium oxides. Cratering initially increased but decreased as the shear strength of the ball bonds reduced which was attributed to formation of oxides that weakened the bond and caused interfacial failure.…”

Section: Reliability Studies 1980-2002mentioning

confidence: 99%

What is the future of bonding wire? Will copper entirely replace gold?

Breach¹

2010

Gold Bull

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Thermosonic ball bonding is a major interconnect process in microelectronics packaging and is positioned to remain one of the key process technologies available to package designers in the near future. However, the main wire material used in fine pitch (FP) and ultra-fine pitch (UFP) ball bonding is gold and with significant increases in gold price, gold ball bonding has become a more costly process that has a considerable economic effect on the assembly of packages used in consumer electronics. An alternative wire material to gold is copper, which is much cheaper and has several technical benefits including better electrical conductivity and has been widely used in discrete and power devices with wire diameters typically larger than 30μm in diameter for many years. However, copper wire behaves quite differently than gold due to its different physical properties, some of which are beneficial and others detrimental to bonding performance. In this article, we briefly review some of the advantages and difficulties with using copper wire advanced packaging and explain why copper cannot replace gold in many applications and why gold offers significant benefits.

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Section: Reliability Studies 1980-2002mentioning

confidence: 99%

What is the future of bonding wire? Will copper entirely replace gold?

Breach¹

2010

Gold Bull

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“…Among these techniques, the wire bonding technology is a technique which connects aluminium pad of chip with lead frame of package by gold wire and is already a very commonly used technology. But recently defects in this wire bonding are increasing (Tan et al, 2002;Goh et al, 2013). As well known, many kinds of chemicals are used and various kinds of particles form in the semiconductor manufacturing process and airborne molecular contaminations (AMCs) from these chemicals.…”

Section: Introductionmentioning

confidence: 99%

Influence of Fluoride Ions Contamination in Front Opening Unified Pod (FOUP) Generating Defective Bonding Pad

Kwon

Hwang

Kim

et al. 2017

Aerosol Air Qual. Res.

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We analyzed defective bonding pad in various ways and determined the causes of defects that boosts oxidation of aluminium by fluoride residue on surface of pad with moisture. Additionally, we compared and evaluated methods to minimize pad defects in aspects such as etching and wafer storage environment. In case of wafers after pad open etching process using common CF 4 stored in FOUP, the concentration of fluoride ions in FOUP was 230 ng L -1 and it decreased down to 170 ng L -1 when Ar sputtering step was added after using CF 4 . Also under the same condition, fluoride ion concentration in FOUP decreased down to 20 ng L -1 when nitrogen purge was introduced for 10 minutes to the FOUP where wafers were stored and the moisture also decreased from 40% before purge to 10% after purge. As a result of observation on pad surface after storing wafers in FOUP for 120 hours under each condition, negligible amount of defects were found when nitrogen was purged. Therefore, we conclude that defects on pad were generated by existing fluoride ions after etching process and moisture in the air.

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“…Cu ball bond is more susceptible to moisture corrosion compared to gold ball bonds and undergo different corrosion mechanisms in microelectronic packaging [19][20][21]. There are different ball bonds corrosion mechanisms of Au and Cu ball bond under humid reliability test.…”

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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Corrosion study at Cu–Al interface in microelectronics packaging

Cited by 92 publications

References 8 publications

What is the future of bonding wire? Will copper entirely replace gold?

What is the future of bonding wire? Will copper entirely replace gold?

Influence of Fluoride Ions Contamination in Front Opening Unified Pod (FOUP) Generating Defective Bonding Pad

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

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