Tradeoff Characteristics Between Resistivity and Reliability for Scaled-Down Cu-Based Interconnects

Yokogawa, Shinji; Kikuta, K.; Tsuchiya, Hiroyuki; Takewaki, T.; Suzuki, Masahiro; Toyoshima, Hideo; Kakuhara, Y.; Kawahara, N.; Usami, T.; Ohto, K.; Fujii, Kiyoshi; Tsuchiya, Yumi; Arita, Koji; Motoyama, K.; Tohara, Makoto; Taiji, T.; Kurokawa, T.; Sekine, Makoto

doi:10.1109/ted.2007.910619

Cited by 26 publications

(13 citation statements)

References 20 publications

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“…We previously reported on the relationship between line resistivity and EM reliability in Cu alloy interconnects and metal-capped Cu interconnects paying attention to the effect of impurity doping with 90-nm-node technology. 2) We showed that Cu alloy interconnects improved EM reliability and increased line resistivity owing to doped impurities, while metal-capped Cu interconnects showed improvement of EM reliability and suppressed resistivity increase. Furthermore, it has been reported that as lines narrow, the effect of grain boundary diffusion on EM becomes large and EM lifetime decreases owing to a small Cu grain size.…”

Section: Introductionmentioning

confidence: 81%

“…As the ways to achieve highly reliable Cu interconnects, applications of Cu alloy interconnects and metalcapped Cu interconnects have been proposed. 2) Cu alloy interconnects are fabricated by doping impurities from a Cu alloy seed layer or a barrier metal layer. As a seed layer, CuAl, [3][4][5] CuMn, 6,7) and CuSn 8,9) have been used, whereas as a barrier metal layer, Ti-based layers 10,11) have been used.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Kakuhara

Yokogawa

Ueno

2010

Jpn. J. Appl. Phys.

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As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Kakuhara

Yokogawa

Ueno

2010

Jpn. J. Appl. Phys.

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“…This native oxide would be reduced to copper in the case of direct deposition of the dielectric cap. The second contribution might be related to the change of the surface scattering for a CoWP interface compared to the interface with a dielectric material [10]. Diffusion of Co into the copper might also contribute to the resistance increase since a number of high temperatures steps are part of the dual damascene process flow.…”

Section: Electrical Performance and Reliabilitymentioning

confidence: 99%

Integration Aspects of CoWP Capping Layers for Electromigration Enhancement

Preuße¹,

Seidel²,

Aubel³

et al. 2008

2008 International Interconnect Technology Conference

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CoWP metal caps have been integrated into 65nm-and 45nm-node copper interconnects. A number of CoWP specific integration aspects have been investigated. Electrical performance, reliability and yield potential were characterized on a statistical base. Substantial progress has been made to suppress the CoWP related time-depended dielectric breakdown (TDDB) degradation making CoWP the option to solve the electromigration (EM) challenge for 32nm and beyond.

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“…[3][4][5] To overcome the issue of EM degradation, several advanced process technologies, labeled ''EM boosters'', have been proposed. However, the trade-off of improving the EM is an increase in resistivity, [6][7][8][9][10] which contributes to a temperature increase due to JH. In order to permit a higher current density limit with a long lifetime, establishing a method for evaluating JH is required.…”

Section: Introductionmentioning

confidence: 99%

Thermal Transient Response and Its Modeling for Joule Heating in Cu/Low-κ Interconnects Under Pulsed Current

Yokogawa

Tsuchiya

Shimizu

2012

Jpn. J. Appl. Phys.

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Solution scattering from iodine in different solvents is used to derive the crosscorrelation between iodine and the solvent. In parallel, molecular dynamics simulations are performed and the findings compared to the experimental results. The close correspondence shows that it is possible to describe the structural rearrangements of the solvent around a solute molecule. Timeresolved studies of photoexcited molecules will therefore allow one to study the relaxations of the solute as well as the solvent molecules.

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Tradeoff Characteristics Between Resistivity and Reliability for Scaled-Down Cu-Based Interconnects

Cited by 26 publications

References 20 publications

Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Comparison of Lifetime Improvements in Electromigration between Ti Barrier Metal and Chemical Vapor Deposition Co Capping

Integration Aspects of CoWP Capping Layers for Electromigration Enhancement

Thermal Transient Response and Its Modeling for Joule Heating in Cu/Low-κ Interconnects Under Pulsed Current

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