Self-sealing complex oxide resonators

TL;DR

This study introduces a self-sealing method using complex oxide membranes to improve hermetic sealing in nano-mechanical pressure sensors, significantly enhancing gas barrier properties through annealing.

Contribution

The paper demonstrates a novel self-sealing technique with complex oxides that enhances hermeticity in pressure sensors via annealing, improving interface adhesion and gas barrier performance.

Findings

Permeation time constants improved up to 4 orders of magnitude after annealing.

Enhanced adhesion at the interface confirmed by ultrasonics showing 70% increase in stiffness.

Self-sealing method is simple and effective for ultrathin hermetic pressure sensors.

Abstract

Although 2D materials hold great potential for next-generation pressure sensors, recent studies revealed that gases permeate along the membrane-surface interface that is only weakly bound by van der Waals interactions, necessitating additional sealing procedures. In this work, we demonstrate the use of free-standing complex oxides as self-sealing membranes that allow the reference cavity of pressure sensors to be sealed by a simple anneal. To test the hermeticity, we study the gas permeation time constants in nano-mechanical resonators made from SrRuO3 and SrTiO3 membranes suspended over SiO2/Si cavities which show an improvement up to 4 orders of magnitude in the permeation time constant after annealing the devices for 15 minutes. Similar devices fabricated on Si3N4/Si do not show such improvements, suggesting that the adhesion increase over SiO2 is mediated by oxygen bonds that are formed at the SiO2/complex oxide interface during the self-sealing anneal. We confirm the enhancement of adhesion by picosecond ultrasonics measurements which show an increase in the interfacial stiffness by 70% after annealing. Since it is straigthforward to apply, the presented self-sealing method is thus a promising route toward realizing ultrathin hermetic pressure sensors.