Voiding Phenomena in Copper-Copper Bonded Structures: Role of Creep

Gondcharton, P.; Imbert, B.; Benaissa, L.; Verdier, Maud

doi:10.1149/2.0081503jss

Cited by 23 publications

(23 citation statements)

References 29 publications

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“…2(d)-(f) show the same three structures after an annealing of two hours at 400°C under nitrogen atmosphere. Following previous reported mechanisms [8], a vertical grain growth and voids are observed in the (i) Cu-Cu bonding structure ( Fig. 2(d)).…”

Section: Methodssupporting

confidence: 83%

Wafer level metallic bonding: Voiding mechanisms in copper layers

Imbert

Gondcharton

Benaissa

et al. 2015

2015 IEEE International Interconnect Technology Conference and 2015 IEEE Materials for Advanced Metallization Conference (IITC/

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Promoted by the component miniaturization trend, three-dimensional integration appears as a promising option for implementation of the next generation of integrated circuits. In this context, copper is still an interesting material to be integrated to vertical interconnexion through direct metal-metal bonding processes. However, it was already reported that voiding phenomena occur in bonded copper layers for temperature beyond 300°C leading to serious reliability problems. This paper aims at explaining voiding mechanisms in the specific metal bonding configuration. Voiding characteristics are compared in different structures allows highlighting several thermal effects. It appears that the mechanical stress sustained by copper layers during post-bonding thermal processes is the main contribution in the voiding phenomenon. Creep mechanisms occurring in polycrystalline copper structure could be considered as the origin of this phenomenon. This study offers better understanding of reliability problems in structures involving encapsulated copper layers and can be used as guideline for metal bonding integration.

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Section: Methodssupporting

confidence: 83%

Wafer level metallic bonding: Voiding mechanisms in copper layers

Imbert

Gondcharton

Benaissa

et al. 2015

2015 IEEE International Interconnect Technology Conference and 2015 IEEE Materials for Advanced Metallization Conference (IITC/

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“…Various experimental studies including Hobbs et al [31], Wang et al [32] and Gondcharton et al [33]) have shown the presence of voids in copper material. Therefore, it is relevant to consider an example of copper material for the purpose of numerical illustration of theoretical results.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Therefore, it is relevant to consider an example of copper material for the purpose of numerical illustration of theoretical results. To illustrate the dependence of amplitude ratios of various reflected waves on the angle of incidence, impedance parameter and other material parameters, the following relevant physical constants of copper material are taken as in Chirita and Danescu [25] and Bucur [27], that is, For the above values of material parameters, the nonhomogeneous systems (32) and (33) Fig. 2 by solid lines, when impedance parameter Z = 0.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Reflection of Plane Waves from Surface of a Generalized Thermo-viscoelastic Porous Solid Half-space with Impedance Boundary Conditions

Baljeet¹

2018

CMST

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A phenomenon of reflection of plane waves from a thermally insulated surface of a solid half-space is studied in the context of Lord-Shulman theory of generalized thermo-viscoelasticity with voids. The governing equations of generalized thermo-viscoelastic medium with voids are specialized in x-z plane. The plane wave solution of these equations shows the existence of three coupled longitudinal waves and a shear vertical wave in a generalized thermo-viscoelastic medium with voids. For incident plane wave (longitudinal or shear), three coupled longitudinal waves and a shear vertical wave reflect back in the medium. The mechanical boundary conditions on the free surface of solid half-space are considered as impedance boundary conditions, in which the shear force tractions are assumed to vary linearly with the tangential displacement components multiplied by the frequency. The impedance corresponds to the constant of proportionality. The appropriate potentials of incident and reflected waves in the half-space will satisfy the required impedance boundary conditions. A non-homogeneous system of four equations in the amplitude ratios of reflected waves is obtained. These amplitude ratios are functions of material parameters, impedance parameter, angle of incidence, thermal relaxation and speeds of plane waves. Using relevant material parameters for medium, the amplitude ratios are computed numerically and plotted against certain ranges of the impedance parameter and the angle of incidence.

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“…This specific shape is due to the copper interdiffusion. In the case of non polished copper surface, the created voids are much larger but the bonding interface is also perfectly sealed as shown in [13].…”

Section: A Wafer-level Bondingmentioning

confidence: 96%

Solderless Leadframe Assisted Wafer-Level Packaging Technology for Power Electronics

Vladimirova

Widiez

Letowski

et al. 2018

2018 IEEE 68th Electronic Components and Technology Conference (ECTC)

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This paper presents a wafer-level pre-packaging technology for power devices. The concept consists in the implementation of a thick 3D patterned copper leadframe ensuring the interconnections of the power devices among them or with the other components of the converter. The metallic leadframe is bonded between two wafers of semiconductor devices enabling the 3D power module integration by the 3D stacking of one or multiple switching cells. Specific technology developments are introduced, practical realizations of the concept are presented and the electrical characterizations of the first prototypes are discussed.

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Voiding Phenomena in Copper-Copper Bonded Structures: Role of Creep

Cited by 23 publications

References 29 publications

Wafer level metallic bonding: Voiding mechanisms in copper layers

Wafer level metallic bonding: Voiding mechanisms in copper layers

Reflection of Plane Waves from Surface of a Generalized Thermo-viscoelastic Porous Solid Half-space with Impedance Boundary Conditions

Solderless Leadframe Assisted Wafer-Level Packaging Technology for Power Electronics

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