Intrinsic low dielectric behaviour of a highly thermally stable Sr-based metal–organic framework for interlayer dielectric materials

Abstract

A Sr-based metal–organic framework {[Sr₂(1,3-bdc)₂(H₂O)₂]·H₂O}_n (1) was synthesized under hydrothermal conditions by the reaction of Sr(NO₃)₂ and 1,3-bis(4,5-dihydro-2-oxazolyl)benzene. A single-crystal X-ray diffraction analysis revealed that compound 1 adopts a 2D layer structure with a monoclinic (C2/c) space group. The distance between the layers of the structure adjusts upon the removal of the water molecules from 95 °C to 330 °C. In addition, the dehydrated compound 1′ retains its crystalline morphology and shows a high thermal stability at temperatures of up to 420 °C. Significantly, the dehydrated compound 1′ has a very low dielectric constant (2.4), suggesting that it might be useful as an interlayer dielectric in integrated circuits. As indicated by impedance spectroscopy, such low dielectric constant behavior is due to the intrinsic nature of the bulk material. The preparation of a low dielectric constant Sr-based metal–organic framework with a high thermal stability opens new directions for research into its applications.