Cu Wafer Bonding for 3D IC Applications

Chen, Kuan‐Neng; Tan, Chuan Seng; Fan, Andy; Reif, L. Rafael

doi:10.1007/978-0-387-76534-1_6

Cited by 12 publications

(6 citation statements)

References 15 publications

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“…Bonding with a compression force: Diffusion bonding.-The thermal compression bonding is a well known technique. [8][9][10] Wafers or dies are pressed together with a controlled force in a bonding tool, while heating is applied (400 C) to allow the bonding diffusion mechanism. Thanks to the compression force, the surfaces roughness is not a limiting factor as the surface asperities are deformed at the bonding interface, therefore surfaces with a roughness in the range of 5 nm can be used.…”

Section: Hybridization Techniques Reviewmentioning

confidence: 99%

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

Cioccio

Gueguen

Taibi

et al. 2011

J. Electrochem. Soc.

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An overview of the different metal bonding techniques used for 3D integration is presented. Key parameters such as surface preparation, temperature and duration of annealing, achievable wafer-to-wafer alignment and electrical results are reviewed. A special focus is done on direct bonding of patterned metal/dielectric surfaces. A mechanism for copper direct bonding is proposed based on bonding toughness measurements, SAM, XRR, XRD, and TEM analysis. Dedicated characterization techniques for such bonding are presented.Bonding of metal surfaces is extensively used for MEMS sealing, power devices, heat dissipation or 3D interconnections. For these applications, techniques such as thermo compression, with or without eutectic alloys or adhesives layers, bumps with low temperature solders or direct bonding are extensively implemented techniques. 1-7 Moreover, for More Moore and More than Moore applications, low temperature bonding and metal bonding are becoming the main drivers of the latest developments. As copper is the main metal used for CMOS interconnects, a high-density Cu interconnection between layer structures, is expected for future three-dimensional integration of electronic devices fabricated on the basis of different technology/ design concepts. In this paper, an overview of the different metal bonding techniques used for 3D integration is presented. Key parameters such as surface preparation, temperature and duration of annealing, achievable alignment and electrical results are reviewed. A special focus is done on direct bonding of patterned metal/dielectric surfaces. A mechanism for copper direct bonding is proposed based on bonding toughness measurements, SAM, XRR, XRD and TEM analysis. Dedicated characterization techniques for such bonding are presented. Hybridization Techniques ReviewCopper is the most (compared to other possible bonding metals) promising candidate for 3D integration technology either for TSV filling or interstata hybridizing. The main reasons of this choice is the widely use of copper in semiconductor device industries and the cost of ownership. On the other hand, the choice of the metal bonding technique is still an open question. Bonding anneal temperature, duration of the annealing, need of an underfill, size and pitch of the interconnect pads, availability of the technique for wafer bonding or die bonding are key parameters of the final choice. The main studied bonding techniques can be divided into two groups: with and without thermal compression.Bonding with a compression force: Diffusion bonding.-The thermal compression bonding is a well known technique. 8-10 Wafers or dies are pressed together with a controlled force in a bonding tool, while heating is applied (400 C) to allow the bonding diffusion mechanism. Thanks to the compression force, the surfaces roughness is not a limiting factor as the surface asperities are deformed at the bonding interface, therefore surfaces with a roughness in the range of 5 nm can be used. Copper oxide should be avoided or removed right before ...

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Section: Hybridization Techniques Reviewmentioning

confidence: 99%

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

Cioccio

Gueguen

Taibi

et al. 2011

J. Electrochem. Soc.

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show abstract

“…The thermal compression bonding is a well known technique [9,10]. Wafers or dies are pressed together with a controlled force in a bonding tool, while heating is applied (400°C) to allow the bonding diffusion mechanism as shown in Figure 1.…”

Section: Hybridization Techniques Reviewmentioning

confidence: 99%

(Invited) An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

Cioccio¹,

Gueguen²,

Taibi³

et al. 2010

ECS Trans.

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“…It has also been highly developed to introduce vertical electrical connections, to provide mechanical support, and to achieve hermetic seal. 2,3 Since Cu is widely used as a metallization layer in modern integrated circuit (IC) manufacturing, Cu-Cu direct bonding is compatible with the current silicon (Si) process technology. 4 Given that this technique is a solder-less process, the final physical properties and reliability of the Cu-Cu bonds are significantly improved over those of conventional solders.…”

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confidence: 99%

Time-Dependent Evolution Study of Ar/N₂ Plasma-Activated Cu Surface for Enabling Two-Step Cu-Cu Direct Bonding in a Non-Vacuum Environment

Goh

Tao

et al. 2021

ECS J. Solid State Sci. Technol.

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In this paper, a two-step copper-copper direct bonding process in a non-vacuum environment is reported. Time-dependent evolution of argon/nitrogen plasma-activated copper surface is carefully studied. A multitude of surface characterizations are performed to investigate the evolution of the copper surface, with and without argon/nitrogen plasma treatment, when it is exposed to the cleanroom ambient for a period of time. The results reveal that a thin layer of copper nitride is formed upon argon/nitrogen plasma activation on copper surface. It is hypothesized that the nitride layer could dampen surface oxidation. This allows the surface to remain in an “activated” state for up to 6 hours. Afterwards, the activated dies are physically bonded at room temperature in cleanroom ambient. Thereafter, the bonded dies are annealed at 300ºC for varying duration, which results in an improvement of the bond strength by a factor of 70 ~ 140 times. A sample bonded after plasma activation and 2-hour cleanroom ambient exposure demonstrates the largest shear strength (~5 MPa). The degradation of copper nitride layer at elevated temperature could aid in maintaining a localized inert environment for the initial diffusion of copper atoms across the interface. This novel bonding technique would be useful for high-throughput three-dimensional wafer bonding and heterogeneous packaging in semiconductor manufacturing.

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Cu Wafer Bonding for 3D IC Applications

Cited by 12 publications

References 15 publications

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

(Invited) An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

Time-Dependent Evolution Study of Ar/N₂ Plasma-Activated Cu Surface for Enabling Two-Step Cu-Cu Direct Bonding in a Non-Vacuum Environment

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Cu Wafer Bonding for 3D IC Applications

Cited by 12 publications

References 15 publications

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

(Invited) An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization

Time-Dependent Evolution Study of Ar/N2 Plasma-Activated Cu Surface for Enabling Two-Step Cu-Cu Direct Bonding in a Non-Vacuum Environment

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Time-Dependent Evolution Study of Ar/N₂ Plasma-Activated Cu Surface for Enabling Two-Step Cu-Cu Direct Bonding in a Non-Vacuum Environment