Optimization of Mesa Etch for a Quasi-Vertical GaN Schottky Barrier Diode (SBD) by Inductively Coupled Plasma (ICP) and Device Characteristics

The optimization of mesa etch for a quasi-vertical gallium nitride (GaN) Schottky barrier diode (SBD) by inductively coupled plasma (ICP) etching was comprehensively investigated in this work, including selection of the etching mask, ICP power, radio frequency (RF) power, ratio of mixed gas, flow rate, and chamber pressure, etc. In particular, the microtrench at the bottom corner of the mesa sidewall was eliminated by a combination of ICP dry etching and tetramethylammonium hydroxide (TMAH) wet treatment. Finally, a highly anisotropic profile of the mesa sidewall was realized by using the optimized etch recipe, and a quasi-vertical GaN SBD was demonstrated, achieving a low reverse current density of 10−8 A/cm2 at −10 V.

4H-SiC Trench Structure Fabrication with Al2O3 Etching Mask

Trench structure etching is one of the most important processes for the fabrication of 4H-SiC Trench MOSFETs. This paper introduced Al2O3 as an etching mask for the fabrication of trench structures. The effect of dry etching parameters to the shape of trench structures were studied systematically. Micro trenches were successfully eliminated from trench structure etching process and preliminary trench MOSFET test structures were fabricated and characterized.