Electrochemical etching strategy for shaping monolithic 3D structures from 4H-SiC wafers

TL;DR

This paper introduces an electrochemical etching method for shaping complex 3D structures in monolithic 4H-SiC wafers, enabling high-quality, thermally stable devices for advanced photonic and electronic applications.

Contribution

The authors develop a novel electrochemical etching technique using p-doping to define etchable regions, achieving sharp contrasts and high-quality surfaces in SiC structures.

Findings

Successful fabrication of monolithic cantilevers, resonators, and membranes.

High surface quality enhanced by thermal treatment beyond 1550°C.

Versatile approach enabling new functionalities in SiC devices.

Abstract

Silicon Carbide (SiC) is an outstanding material, not only for electronic applications, but also for projected functionalities in the realm of photonic quantum technologies, nano-mechanical resonators and photonics on-a-chip. For shaping 3D structures out of SiC wafers, predominantly dry-etching techniques are used. SiC is nearly inert with respect to wet-etching, occasionally photoelectrochemical etching strategies have been applied. Here, we propose an electrochemical etching strategy that solely relies on defining etchable volumina by implantation of p-dopands. Together with the inertness of the n-doped regions, very sharp etching contrasts can be achieved. We present devices as different as monolithic cantilevers, disk-shaped optical resonators and membranes etched out of a single crystal wafer. The high quality of the resulting surfaces can even be enhanced by thermal treatment, with shape-stable devices up to and even beyond 1550{\deg}C. The versatility of our approach paves the way for new functionalities on SiC as high-performance multi-functional wafer platform.