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Carbon Nanotubes for Interconnect ApplicationsFranz Kreupl,
Andrew P. Graham, Maik Liebau, Georg S. Duesberg, Robert Seidel,
Eugen Unger
Presented at IEDM 2004EE C235 Presentation by Zachery
JacobsonMarch 5, 2007
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OutlineOverview of InterconnectsWhy Carbon Nanotube
interconnects?Growth strategiesResultsIssuesConclusions
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Overview of InterconnectsIncreased resistance and decreased
current carrying capability due to electromigration are two
critical issues affecting the use of copper interconnectsRon Ho,
SLIP 2005ITRS Roadmap, 2005
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Why Carbon Nanotube Interconnects?Metallic Carbon Nanotubes are
potentially viable for use as interconnects due to their large
mean-free path (which leads to low resistance) and low
electromigration (which increases current carrying capability)A.
Naeemi, et al, IEDM 2004F. Kreupl, et al, IEDM 2004
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Growth StrategiesTwo major growth strategiesBottom-up, where
CNTs are grown before ILD depositionBuried catalyst, where CNTs are
grown after ILD deposition
J. Li, et al, Appl. Phys. Lett. 82, 2491 (2003)F. Kreupl, et al,
IEDM 2004
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ResultsNanotube quality is better than PECVD grown nanotubes,
but variability is still highF. Kreupl, et al, IEDM 2004
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ResultsRelatively high annealing temperature needed to reduce
resistance due to contact issuesLarge variability in resistance
between viasF. Kreupl, et al, IEDM 2004
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IssuesContact resistance eliminates any advantage seen versus
bulk Cu interconnectsTo make a good low resistance contact, high
annealing temperatures are required which exceed the thermal
budgetVariability of grown nanotubes continues to be an issueLarge
diameter nanotubes underperform Cu vias even under ideal
conditions
F. Kreupl, et al, IEDM 2004
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ConclusionsCarbon Nanotubes have theoretically higher
performance than Copper interconnects in some applicationsUsing a
buried catalyst method, vias were fabricated using single MWCNTs
down to 20 nm in diameterVariability was high among the nanowires
grown, which has a strong effect on performanceIf good contacts can
be achieved with a low temperature process, carbon nanotubes have a
chance at replacing copper vias at very small process nodes
Thank you for your time! Questions?
