Demonstration and Electrical Performance of Cu–Cu Bonding at 150 °C With Pd Passivation

Huang, Yi-Wen; Chien, Yu-San; Tzeng, Ruoh-Ning; Chen, Kuan‐Neng

doi:10.1109/ted.2015.2446507

Cited by 70 publications

(22 citation statements)

References 16 publications

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“…The necessary condition to attain reliable low temperature, low pressure Cu-Cu bonding primarily lies in the degree of preventing Cu surface from oxidation. One such technique proposed in the literature is to remove the surface oxide with high [48] energetic atom bombardment and bond the Cu surface immediately after the bombardment process at ultra-high vacuum at 7.5 Â 10 À8 torr. These stringent requirements make the process complex and costly.…”

Section: Cu-cu Thermocompression Bonding Using Sammentioning

confidence: 99%

“…Therefore, searching for suitable metal species for Cu passivation with same diffusion behavior as Ti atoms becomes important. Chen and coworkers further reported that Cu-Cu bonding with Pd passivation could be demonstrated at low temperature (150 C) with superior electrical performance compared to Ti passivation [48,49], as shown in Fig. 4.…”

Section: Cu-cumentioning

confidence: 99%

“…4. Furthermore, reliability assessments, including current stressing, temperature cycling, and unbiased highly accelerated stress test were demonstrated along with interdiffusion behavior [48]. All the metal-based passivation techniques proposed across the globe not only help in reducing the bonding temperature to below 200 C but also provides reliable and quality Cu-Cu bonding.…”

Section: Cu-cumentioning

confidence: 99%

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Low Temperature Cu–Cu Bonding Technology in Three-Dimensional Integration: An Extensive Review

Panigrahy

Kuan-Neng

2018

Journal of Electronic Packaging

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Arguably, the integrated circuit (IC) industry has received robust scientific and technological attention due to the ultra-small and extremely fast transistors since past four decades that consents to Moore's law. The introduction of new interconnect materials as well as innovative architectures has aided for large-scale miniaturization of devices, but their contributions were limited. Thus, the focus has shifted toward the development of new integration approaches that reduce the interconnect delays which has been achieved successfully by three-dimensional integrated circuit (3D IC). At this juncture, semiconductor industries utilize Cu–Cu bonding as a key technique for 3D IC integration. This review paper focuses on the key role of low temperature Cu–Cu bonding, renaissance of the low temperature bonding, and current research trends to achieve low temperature Cu–Cu bonding for 3D IC and heterogeneous integration applications.

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Section: Cu-cu Thermocompression Bonding Using Sammentioning

confidence: 99%

Section: Cu-cumentioning

confidence: 99%

Section: Cu-cumentioning

confidence: 99%

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Low Temperature Cu–Cu Bonding Technology in Three-Dimensional Integration: An Extensive Review

Panigrahy

Kuan-Neng

2018

Journal of Electronic Packaging

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“…Much research on low temperature Cu-to-Cu bonding has been reported [4][5][6][7][8][9][10][11][12][13][14]. The research includes coverage of surface activated bonding [4], passivation using a self-assembled monolayer [5], wet cleaning [6,7], metal passivation with Pd, Mg, Ag, or Au [8][9][10][11], Cu (111) crystal plane studies [12], Cu/SiO 2 hybrid bonding [3,13], and Cu/polymer hybrid bonding [14]. So far, the direct bonding interconnect (DBI) technique by Ziptronix [13] has been considered the most adoptable Cu bonding process in mass production.…”

Section: Introductionmentioning

confidence: 99%

Two-Step Plasma Treatment on Sputtered and Electroplated Cu Surfaces for Cu-To-Cu Bonding Application

2019

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The technology trends of next generation electronic packaging are moving toward heterogeneous 3D packaging systems. One of the key processes of 3D packaging system is Cu-to-Cu bonding, which is highly dependent on the planarized, activated, and oxygen-free Cu surface. A two-step plasma treatment is studied to form a Cu surface that does not react with oxygen and improves the Cu bonding interface quality at low bonding temperature (300 °C). In this study, the effects of two-step plasma treatment on both sputtered and electroplated Cu surfaces were evaluated through structural, chemical, and electrical analysis. The Cu bonding interface was studied by scanning acoustic tomography analysis after the thermocompression bonding process. Both sputtered and electroplated Cu thin films had the preferred orientation of (111) plane, but sputtered Cu exhibited larger grains than the electroplated Cu. As a result, the roughness of sputtered Cu was lower, and the resistivity was higher than that of electroplated Cu. Based on X-ray photoelectron spectroscopy analysis, the sputtered Cu formed more copper nitrides and fewer copper oxides than the electroplated Cu. A significant improvement in bonding quality at the Cu bonded interface was observed in sputtered Cu.

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“…However, application of such a high pressure condition during bonding may damage the delicate underneath Cu interconnect and seriously affect the system performance. Also, the same research group proposed a noble metal based Cu surface passivation technique using Pd prior to wafer-level Cu-Cu bonding at low temperature (150 C) and very high pressure of 1.91 MPa with superior electrical performance than Ti based Cu-Cu bonding [30]. But very high bonding pressure deviates from the need of low temperature and low pressure Cu-Cu bonding.…”

Section: Introductionmentioning

confidence: 99%

Metal-Alloy Cu Surface Passivation Leads to High Quality Fine-Pitch Bump-Less Cu-Cu Bonding for 3D IC and Heterogeneous Integration Applications

Panigrahy¹,

Bonam

et al. 2018

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

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Abstract-In this paper, we report a low temperature, finepitch, bump-less, damascene compatible Cu-Cu thermocompression bonding, using an optimized ultra-thin passivation layer, Constantan, which is an alloy (CopperNickel) of 55% Cu and 45% Ni. Surface oxidation and its roughness are the major bottlenecks in achieving high quality, low temperature, and fine-pitch Cu-Cu bonding. In this endeavor, we have used Cu rich alloy (Constantan) for passivation of Cu surface prior to bonding. We have systematically optimized the constantan passivation layer thickness for high quality low temperature, low pressure, bump-less Cu-Cu bonding. Also, we have studied systematically the efficacy of Cu surface passivation with optimized ultra-thin constantan alloy passivation layer. After rigorous trial and optimization, we successfully identified 2 nm passivation layer thickness, at which very high quality Cu-Cu bonding could be accomplished at sub 200 ˚C with a nominal contact pressure of 0.4 MPa. Post-bonding, electrical and mechanical characterization were validated using four-probe IV measurement and bond strength measurement respectively. Furthermore, Cu-Cu bonding interface was analyzed using IR wafer bonder inspection tool. Very high bond strength of 163 MPa and defect free interface observed by WBI-IR clearly suggests, Cu-Cu fine-pitch bonding with optimized ultra-thin alloy of 2 nm thick constantan, is of very high quality and reliable. Moreover, this novel bonding approach with alloy based interconnect passivation technique is the prime contestant for future heterogeneous integration.

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Demonstration and Electrical Performance of Cu–Cu Bonding at 150 °C With Pd Passivation

Cited by 70 publications

References 16 publications

Low Temperature Cu–Cu Bonding Technology in Three-Dimensional Integration: An Extensive Review

Low Temperature Cu–Cu Bonding Technology in Three-Dimensional Integration: An Extensive Review

Two-Step Plasma Treatment on Sputtered and Electroplated Cu Surfaces for Cu-To-Cu Bonding Application

Metal-Alloy Cu Surface Passivation Leads to High Quality Fine-Pitch Bump-Less Cu-Cu Bonding for 3D IC and Heterogeneous Integration Applications

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