Ultrahigh GaN:SiO₂etch selectivity byin situsurface modification of SiO₂in a Cl₂-Ar plasma

Abstract

The realization of vertical GaN devices requires deep plasma etching and is contingent on high mask selectivity. In this work, we show that SiO 2 can be an effective mask material for deep etching GaN with GaN:SiO 2 selectivities greater than 40-higher than the conventionally reported 15 for metal hard masks such as nickel. Ultrahigh SiO 2 selectivities were achieved by introducing Al and AlCl into the Cl 2-Ar inductively coupled plasma, which reacts with the SiO 2 mask surface to form an etchresistant aluminum silicate surface layer. This mechanism provides a low-contamination pathway to etch deep GaN microdevices. IMPACT STATEMENT This manuscript reports on exceptionally high GaN:SiO 2 etch selectivities in a Cl 2-Ar plasma which will enable fabrication of new classes of GaN device structures that currently only exist in theory.

Local pressure calibration method of inductively coupled plasma generator based on laser Thomson scattering measurement

“…Inductively Coupled Plasma (ICP) has been widely used for crystal etching 1 , semiconductor etching 2 , thin film deposition 3 , material surface modification 4 , 5 and so on. However, accurate and skilled use of these processes requires a clear understanding of the various ICP control factors such as ICP internal pressure and absorbed power.…”

Validation of inductively coupled plasma simulation model by laser Thomson scattering experiment

“…2021 b ) and material surface modification (Frye et al. 2021). Accurate and proficient use of the ICP process requires a clear understanding of the various ICP control factors, such as the gas pressure and absorbed power of the ICP.…”