Understanding Electromigration in Cu-CNT Composite Interconnects: A Multiscale Electrothermal Simulation Study

• Published in: IEEE transactions on electron devices Vol. 65; no. 9; pp. 3884 - 3892
• Main Authors: Lee, Jaehyun, Berrada, Salim, Adamu-Lema, Fikru, Nagy, Nicole, Georgiev, Vihar P., Sadi, Toufik, Liang, Jie, Ramos, Raphael, Carrillo-Nunez, Hamilton, Kalita, Dipankar, Lilienthal, Katharina, Wislicenus, Marcus, Pandey, Reeturaj, Chen, Bingan, Teo, Kenneth B. K., Goncalves, Goncalo, Okuno, Hanako, Uhlig, Benjamin, Todri-Sanial, Aida, Dijon, Jean, Asenov, Asen
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Activation energy; Carbon nanotubes; Composite materials; Conductivity; Contacts; Cu-carbon nanotubes (CNT) composites; Density functional theory; density functional theory (DFT); Discrete Fourier transforms; Electric contacts; Electrical resistivity; Electromigration; electromigration (EM); electrothermal; Engineering Sciences; Heating; Interconnections; interconnects; Lattices; Lorenz number; Micro and nanotechnologies; Microelectronics; Multiscale analysis; multiscale simulation; Resistance; self-heating; Simulation; Thermal conductivity; Thermodynamic properties; Interconnect; Electromigration; DFT; Self-heating; Cu-CNT composites; Multi-scale simulation; Electro-thermal coupling
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2018.2853550

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.