Role of process parameters on bondability and pad damage indicators in copper ball bonding

Qin, Ivy; Shah, A.; Huynh, Cuong; Meyer, M.; Mayer, Michael; Zhou, Yunhong

doi:10.1016/j.microrel.2010.04.001

Cited by 27 publications

(4 citation statements)

References 26 publications

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“…Understanding the dynamic behaviors is essential for assembly processes in the semiconductor industry. [1] For example, in the copper (Cu) wire-bonding process, the free air ball (FAB) is compressed against the bond pad of the integrated circuit (IC) chips, and the contact force reaches a required value in a few milliseconds. [2,3] In such cases, the rapid increase of loading rates causes different deformation of the thin-film stacked structure of bond pads due to the strain rate dependence of the materials.…”

Section: Introductionmentioning

confidence: 99%

A new method for the dynamic deformation characterization of thin-film stacked structures

et al. 2021

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The dynamic deformation of thin-film stacked structures in the bond pad of microelectronic devices usually occurs when the contact load rapidly increases during the wire-bonding process. This work developed dynamic strain rate model for analyzing the dynamic response of thin-film stacked structures at varying loading rates. Dynamic strain rate tests were performed by maintaining the ratio of instantaneous load rate to load. The indentation stress-strain curves at different testing protocols were plotted. We found that the deformation decreased as the prescribed rate increased because of the rate-dependent characteristics of the thin Cu film.

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Section: Introductionmentioning

confidence: 99%

A new method for the dynamic deformation characterization of thin-film stacked structures

et al. 2021

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“…However, due to increase of Au price in recent years, there is an emerging trend to use copper (Cu) to replace Au in wire bonding because Cu wire not only has lower cost but also has superior electrical, mechanical and thermal properties compared to Au wire. However, Cu free air ball (FAB) is much harder than Au FAB ball so that there are several challenges for applying Cu wire bond such as excessive deformation of the Al bond pad and dielectric layer crack under the bond pads caused by high amount of stress induced by contact force and ultrasonic energy [1][2][3]. Stress induced by bond force and ultrasonic dissipation during wire bonding can be measured in-situ using stress sensor and the influence of bonding parameters (bond force, bond power and temperature) can be studied through stress sensor designed in chip [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Study on failure mode and mechanism of bond pad under Cu ball bonding process using wire pull test and finite element modeling

Wai

Hsiao

et al. 2015

2015 IEEE 17th Electronics Packaging and Technology Conference (EPTC)

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In this work, wire pull test combined with finite element analysis (FEA) were conducted to investigate failure mode and failure criterion for bond pad reliability assessment under Cu wire bond process. Pull test was conducted for bonded Cu wires with different pull locations changing from the first ball bond to the second wedge bond. Failure forces were recorded and failure site and modes were studied. The effect of pull location on failure mode was observed. Failure modes change from wire neck broken, ball lift, pad peel to wedge broken when pull location is changing from the first bond towards the second bond. Based on wire pull test and FEA simulation results, failure mechanism and failure criterion were developed for different Cu wire bond failure modes. The effects of wire loop height on pull test results and modeling stress were also investigated.

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“…The contact force is related to the out-of-plane stress, which is a potential factor leading to structural cracks and delamination (Shen et al, 2006;Yeo, 2017). Moreover, different loading rates in the contact stage are also a possible result of cracking (Toyozawa et al, 1990;Qin et al, 2011) However, there is no reliable instrumented testing methodology to correlate the control parameters of the wire-bonding process and the mechanical behavior and damage modes of the bond pad (Charles, 2016).…”

Section: Fig 22mentioning

confidence: 99%

Dynamic damage analysis of thin film stacked structures for microelectronic devices

Zhao¹

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In the context of the megatrends of remote working, the development of artificial intelligence, and electric vehicle applications, there is a great demand for betterperforming and multi-functional integrated circuit (IC) chips to fill the technology gaps.Moreover, the demand for package minimization and rapid production of power electronic products have raised a serious concern about the robustness of thin-film stacked structures in the bond pad of IC chips, especially in the processes of wirebonding, wafer probing, and die ejection.Recently, hard copper (Cu) wires have been widely applied to replace traditional soft gold (Au) wires in the wire-bonding process. It is not only because the price of Cu wires is more competitive than that of Au wires, but also Cu wires possess superior electrical, mechanical, and thermal properties over Au wires. However, the dynamic contact between the Cu free air ball (FAB) and the bond pad surface leads to excessive deformation and thus significant damage or failure in the brittle substrate beneath the top metallization pad of IC chips. Moreover, the damaged sites are invisible, which makes it difficult to predict their occurrences. Hence, this research aims to study the dynamic deformation and damage behavior of the thin-film stacked structure during high strain-rate indentation loading through experimental, statistical, and analytical methods.First, a dynamic strain-rate (DSR) model has been developed for analyzing the dynamic response of a thin-film stacked structure consisting of a top metallization layer (copper-titanium CuTi) and an intermediate dielectric layer (silicon nitride Si3N4) on the Si substrate at varying loading rates. In the DSR model, the exponential indentation strain rate-time history is established by maintaining the constant ratio of the Abstract X instantaneous loading rate to load (Ṗ/P) in the indentation tests. The relationship between the indentation strain rate and indentation strain at different Ṗ/P was analyzed for characterizing the DSR model. The indentation stress-strain curves at different testing protocols were plotted to investigate the rate-dependent behaviors of the thinfilm stacked structure. Second, DSR indentation tests integrated with the acoustic emission (AE) sensingtechnique were conducted on a Si (100) wafer to investigate the phase transformation at low and high Ṗ/P. The occurrence of phase transformation was detected by an AE event and corresponds to an onset load. It was found that high Ṗ/P leads to a decrease in the phase transformation threshold, which could be attributed to an increase in the shear stress with increasing strain rates. The activation volume V* for the onset of phase transformation was determined based on two methods of the strain rate sensitivity and the nucleation theory-based model. Both analysis methods yield comparable V* and well proximate the size of the nucleated β-Sn phase, suggesting that the phase transformation is predominantly induced by shearing under the non-hydrostatic condition. Moreover, an incre...

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Role of process parameters on bondability and pad damage indicators in copper ball bonding

Cited by 27 publications

References 26 publications

A new method for the dynamic deformation characterization of thin-film stacked structures

A new method for the dynamic deformation characterization of thin-film stacked structures

Study on failure mode and mechanism of bond pad under Cu ball bonding process using wire pull test and finite element modeling

Dynamic damage analysis of thin film stacked structures for microelectronic devices

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