Mechanical FEM Simulation of Bonding Process on Cu Lowk Wafers

Degryse, Dominiek; Vandevelde, Bart; Beyne, Eric

doi:10.1109/tcapt.2004.838862

Cited by 47 publications

(21 citation statements)

References 6 publications

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“…[15][16][17][18][19][20][21] Some contributions focus on how ultrasonic stresses affect the microchip. [15][16][17][18][19][20] While the main aspects of ball bonding were covered in these papers, simulations of the ultrasonic parameter during impact of the ball on the pad are scarce. Thus, a numerical method combined with a geometrical model is reported in this paper, describing how the free air ball (FAB) shape transforms in that of the deformed ball, as illustrated in Fig.…”

Section: -9)mentioning

confidence: 99%

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Mayer¹

2013

Journal of the Microelectronics and Packaging Society

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As thermosonic ball bonding is developed for more and more advanced applications in the electronic packaging industry, the control of process stresses induced on the integrated circuits becomes more important. If Cu bonding wire is used instead of Au wire, larger ultrasonic levels are common during bonding. For advanced microchips the use of Cu based wire is risky because the ultrasonic stresses can cause chip damage. This risk needs to be managed by e.g. the use of ultrasound during the impact stage of the ball on the pad ("pre-bleed") as it can reduce the strain hardening effect, which leads to a softer deformed ball that can be bonded with less ultrasound. To find the best profiles of ultrasound during impact, a numerical model is reported for ultrasonic bonding with capillary dynamics combined with a geometrical model describing ball deformation based on volume conservation and stress balance. This leads to an efficient procedure of ball bond modelling bypassing plasticity and contact pairs. The ultrasonic force and average stress at the bond zone are extracted from the numerical experiments for a 50 µm diameter free air ball deformed by a capillary with a hole diameter of 35 µm at the tip, a chamfer diameter of 51 µm, a chamfer angle of 90 o , and a face angle of 1 o . An upper limit of the ultrasonic amplitude during impact is derived below which the ultrasonic shear stress at the interface is not higher than 120 MPa, which can be recommended for low stress bonding.

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Section: -9)mentioning

confidence: 99%

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Mayer¹

2013

Journal of the Microelectronics and Packaging Society

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“…Current issue in the development of new Cu/low-k CMOS technologies is the thermo-mechanical reliability of bondpad structures due to the bad thermal and mechanical integrity of the low-k materials and associated interfaces [17,18]. The resulting forces due to the wire bonding process and subsequent qualification tests, such as wire pull and shear, can easily result in reliability problems like bondpad delamination and low-k cracking.…”

Section: Wire Bondmentioning

confidence: 99%

“…FE techniques are widely used to predict the deformations and stresses and their evolution during IC processes, packaging manufacturing processes, and/or product testing [4,5,8,[17][18][19][20][21][22][23][24][25][26]. Modelling techniques such as contact elements, global-local, sub-structuring, element birth and death, fracture mechanics and material models such as visco-elasticity, plasticity and creep are rapidly developed to predict the stress and strain state in the electronic Fig.…”

Section: Facing the Future: Cmos065 And Beyondmentioning

confidence: 99%

Facing the challenge of designing for Cu/low-k reliability

Driel

2007

Microelectronics Reliability

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“…Au and Al wires have been widely used in wire bonding, but with the new requirements for high-speed and high-power applications, Cu has emerged as a bonding wire of interest. [1][2][3] In general, Cu has good electrical, mechanical, and thermal performance at relatively low cost. However, the reliability of Cu wire bonding has not been comprehensively evaluated.…”

Section: Introductionmentioning

confidence: 99%

Thermal Aging Effects on Cu Ball Shear Strength and Cu/Al Intermetallic Growth

Amistoso

Amorsolo

2010

Journal of Elec Materi

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Intermetallic growth and ball shear behavior of annealed Cu wire bonds on Al have been studied. The shear strength of Cu ball bonds decreased with time, and ductile fracture was the dominant failure mode from 125°C to 150°C. Al pad peel-off occurred as the aging temperature was increased above 150°C. The overall Cu/Al intermetallic thickness exhibited parabolic behavior as a function of time. A linear correlation was established between ball shear strength, metal peel-off occurrence, and intermetallic growth. The Cu/Al intermetallic growth activation energy was 0.23 eV, and the intermetallics identified in the experiment were CuAl 2 and CuAl.

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Mechanical FEM Simulation of Bonding Process on Cu Lowk Wafers

Cited by 47 publications

References 6 publications

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Facing the challenge of designing for Cu/low-k reliability

Thermal Aging Effects on Cu Ball Shear Strength and Cu/Al Intermetallic Growth

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