Enabling Simultaneous Extreme Ultra Low-k in Stiff, Resilient, and Thermally Stable Nano-Architected Materials.

Low dielectric constant (low-k) materials have gained increasing popularity because of their critical role in developing faster, smaller, and higher performance devices. Their practical use has been limited by the strong coupling among mechanical, thermal, and electrical properties of materials and their dielectric constant; a low-k is usually attained by materials that are very porous, which results in high compliance, that is, silica aerogels; high dielectric loss, that is, porous polycrystalline alumina; and poor thermal stability, that is, Sr-based metal-organic frameworks. We report the fabrication of 3D nanoarchitected hollow-beam alumina dielectrics which k is 1.06-1.10 at 1 MHz that is stable over the voltage range of -20 to 20 V and a frequency range of 100 kHz to 10 MHz. This dielectric material can be used in capacitors and is mechanically resilient, with a Young's modulus of 30 MPa, a yield strength of 1.07 MPa, a nearly full shape recoverability to its original size after >50% compressions, and outstanding thermal stability with a thermal coefficient of dielectric constant (TCK) of 2.43 × 10 K up to 800 °C. These results suggest that nanoarchitected materials may serve as viable candidates for ultra low-k materials that are simultaneously mechanically resilient and thermally and electrically stable for microelectronics and devices.