Magnetic Field-Assisted Self-Wound 3-D Nanomembrane Capacitors Bridge the Gap Between MLCC and Trench Capacitor Technologies

Abstract

This letter reports the transformation of large-area planar metal–insulator–metal (MIM) nanomembrane capacitors into compact tubular 3-D architectures. By combining the powerful approach of strain-induced nanomembrane self-assembly with an external magnetic field, a stable winding process over a large distance in the range of centimeters is demonstrated. A wet release platform based on encapsulated methyl cellulose allows to release the planar structures with rates of several $100~\mu \text{m}$ /s from their substrate. Footprint shrinkage factors up to 230 are shown by assembling 24-mm long planar structures into 3-D architectures having 82- $\mu \text{m}$ diameter and ~120 windings. The fabricated capacitors feature a capacitance per footprint up to $1.3~\mu \text{F}$ /mm2 for a 15-nm Al2O3 dielectric with less than 100-nA/ $\mu \text{F}$ leakage at 6 V and improved frequency characteristics. This technology is a promising candidate for bridging the gap between discrete multilayer ceramic capacitor (MLCC) and ON-chip trench capacitor technologies.