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Understanding Electromigration in Cu-CNT Composite Interconnects

A Multiscale Electrothermal Simulation Study
: Lee, J.; Berrada, S.; Adamu-Lema, F.; Nagy, N.; Georgiev, V.P.; Sadi, T.; Liang, J.; Ramos, R.; Carrillo-Nunez, H.; Kalita, D.; Lilienthal, K.; Wislicenus, M.; Pandey, R.; Chen, B.; Teo, K.B.K.; Goncalves, G.; Okuno, H.; Uhlig, B.; Todri-Sanial, A.; Dijon, J.; Asenov, A.


IEEE transactions on electron devices 65 (2018), Nr.9, S.3884-3892
ISSN: 0018-9383
Fraunhofer IPMS ()

In this paper, we report a hierarchical simulation study of the electromigration (EM) problem in Cu-carbon nanotube (CNT) composite interconnects. This paper is based on the investigation of the activation energy and self-heating temperature using a multiscale electrothermal simulation framework. We first investigate the electrical and thermal properties of Cu-CNT composites, including contact resistances, using the density functional theory and reactive force field approaches, respectively. The corresponding results are employed in macroscopic electrothermal simulations taking into account the self-heating phenomenon. Our simulations show that although Cu atoms have similar activation energies in both bulk Cu and Cu-CNT composites, Cu-CNT composite interconnects are more resistant to EM thanks to the large Lorenz number of the CNTs. Moreover, we found that a large and homogenous conductivity along the transport direction in interconnects is one of the most important design rules to minimize the EM.