Overcoming Si3N4 film stress limitations for High Quality factor ring resonators

TL;DR

This paper presents a novel method using mechanical trenches to mitigate stress in silicon nitride films, enabling the fabrication of high-Q ring resonators with record quality factors for photonic applications.

Contribution

Introduction of mechanical trenches to reduce Si3N4 film stress, achieving record high quality factors in ring resonators.

Findings

Achieved a quality factor of 7 million in Si3N4 ring resonators.

Demonstrated propagation loss of 4.2 dB/m.

First report of such high Q for high confinement Si3N4 resonators at 1550 nm.

Abstract

Silicon nitride (Si3N4) ring resonators are critical for a variety of photonic devices. However the intrinsically high film stress of silicon nitride has limited both the optical confinement and quality factor (Q) of ring resonators. We show that stress in Si3N4 films can be overcome by introducing mechanical trenches for isolating photonic devices from propagating cracks. We demonstrate a Si3N4 ring resonator with an intrinsic quality factor of 7 million, corresponding to a propagation loss of 4.2 dB/m. This is the highest quality factor reported to date for high confinement Si3N4 ring resonators in the 1550 nm wavelength range.