Monolithic mtesla-level magnetic induction by self-rolled-up membrane technology.

Monolithic strong magnetic induction at the mtesla to tesla level provides essential functionalities to physical, chemical, and medical systems. Current design options are constrained by existing capabilities in three-dimensional (3D) structure construction, current handling, and magnetic material integration. We report here geometric transformation of large-area and relatively thick (~100 to 250 nm) 2D nanomembranes into multiturn 3D air-core microtubes by a vapor-phase self-rolled-up membrane (S-RuM) nanotechnology, combined with postrolling integration of ferrofluid magnetic materials by capillary force. Hundreds of S-RuM power inductors on sapphire are designed and tested, with maximum operating frequency exceeding 500 MHz. An inductance of 1.24 µH at 10 kHz has been achieved for a single microtube inductor, with corresponding areal and volumetric inductance densities of 3 µH/mm2 and 23 µH/mm3, respectively. The simulated intensity of the magnetic induction reaches tens of mtesla in fabricated devices at 10 MHz.

Monolithic radio frequency SiN x self-rolled-up nanomembrane interdigital capacitor modeling and fabrication.

Monolithic capacitors operating at radio frequencies (RF) serve as critical components in integrated circuits for wireless communication. Design and fabrication innovations for high capacitance density RF capacitors are highly desired for the miniaturization of RFIC chips. However, practical and simple solutions are limited by existing capabilities in three-dimensional (3D) structure construction and the effective configuration of electrodes. We report a unique route to achieve unprecedentedly high capacitance density at a high operating frequency through a capacitor configuration of 3D coil interdigital electrodes using planar semiconductor processing compatible materials and fabrication methods. A systematic mechanical-electrical design principle is demonstrated, and fabricated devices show a maximum 21.5 pF capacitance, which is 17.2× larger after rolling up. The corresponding capacitance density is as large as 371 pF mm-2, with resonant frequency of 1.5 GHz. The performance could be improved significantly by simply rolling up more turns with minimal change to the area footprint.