Thermally conductive ultra-low-k dielectric layers based on two-dimensional covalent organic frameworks

Austin M. Evans, Department of Chemistry, Northwestern University, Evanston, IL, USA.
Ashutosh Giri, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
Vinod K. Sangwan, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
Sangni Xun, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
Matthew Bartnof, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
Carlos G. Torres-Castanedo, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
Halleh B. Balch, Department of Physics, University of California Berkeley, Berkeley, CA, USA.
Matthew S. Rahn, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
Nathan P. Bradshaw, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
Edon Vitaku, Department of Chemistry, Northwestern University, Evanston, IL, USA.
David W. Burke, Department of Chemistry, Northwestern University, Evanston, IL, USA.
Hong Li, Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, USA.
Michael J. Bedzyk, Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
Feng Wang, Department of Physics, University of California Berkeley, Berkeley, CA, USA.
Jean-Luc Brédas, Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, USA.
Jonathan A. Malen, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
Alan J. McGaughey, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
Mark C. Hersam, Department of Chemistry, Northwestern University, Evanston, IL, USA.
William R. Dichtel, Department of Chemistry, Northwestern University, Evanston, IL, USA. wdichtel@northwestern.edu.
Patrick E. Hopkins, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA. peh4v@virginia.edu.

Document Type

Article

Date of Original Version

8-1-2021

Abstract

As the features of microprocessors are miniaturized, low-dielectric-constant (low-k) materials are necessary to limit electronic crosstalk, charge build-up, and signal propagation delay. However, all known low-k dielectrics exhibit low thermal conductivities, which complicate heat dissipation in high-power-density chips. Two-dimensional (2D) covalent organic frameworks (COFs) combine immense permanent porosities, which lead to low dielectric permittivities, and periodic layered structures, which grant relatively high thermal conductivities. However, conventional synthetic routes produce 2D COFs that are unsuitable for the evaluation of these properties and integration into devices. Here, we report the fabrication of high-quality COF thin films, which enable thermoreflectance and impedance spectroscopy measurements. These measurements reveal that 2D COFs have high thermal conductivities (1 W m K) with ultra-low dielectric permittivities (k = 1.6). These results show that oriented, layered 2D polymers are promising next-generation dielectric layers and that these molecularly precise materials offer tunable combinations of useful properties.

Publication Title, e.g., Journal

Nature materials

Volume

20

Issue

8

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