Metal-Assisted Chemical Etching for Anisotropic Deep Trenching of GaN Array

Qi Wang,Yi Huang,Guodong Yuan,Kehong Zhou,Wensheng Yan,Hongsheng Zhang,Shuai Zhao,Wen Yang

doi:10.3390/nano11123179

Abstract

Realizing the anisotropic deep trenching of GaN without surface damage is essential for the fabrication of GaN-based devices. However, traditional dry etching technologies introduce irreversible damage to GaN and degrade the performance of the device. In this paper, we demonstrate a damage-free, rapid metal-assisted chemical etching (MacEtch) method and perform an anisotropic, deep trenching of a GaN array. Regular GaN microarrays are fabricated based on the proposed method, in which CuSO4 and HF are adopted as etchants while ultraviolet light and Ni/Ag mask are applied to catalyze the etching process of GaN, reaching an etching rate of 100 nm/min. We comprehensively explore the etching mechanism by adopting three different patterns, comparing a Ni/Ag mask with a SiN mask, and adjusting the etchant proportion. Under the catalytic role of Ni/Ag, the GaN etching rate nearby the metal mask is much faster than that of other parts, which contributes to the formation of deep trenches. Furthermore, an optimized etchant is studied to restrain the disorder accumulation of excessive Cu particles and guarantee a continuous etching result. Notably, our work presents a novel low-cost MacEtch method to achieve GaN deep etching at room temperature, which may promote the evolution of GaN-based device fabrication.

Highlights

Published: 24 November 2021Metal-assisted chemical etching (MacEtch) is crucial for preparing complex micro/nano-structures such as pores, rings and pillars on Si and other compound semiconductors [1,2]
~100 nm/min; the obtained trench arrays are uniform. Note that this high etching rate is realized with metal-assisted chemical etching (MacEtch) at room temperature, and it is believed to be further improved by raising the reaction temperature
We demonstrate a novel MacEtch method and realize the rapid and anisotropic deep We demonstrate a novel MacEtch method and realize the rapid and anisotropic deep etching of GaN

Summary

Introduction

Metal-assisted chemical etching (MacEtch) is crucial for preparing complex micro/nano-structures such as pores, rings and pillars on Si and other compound semiconductors [1,2]. A promising method, micro-/nano-structures in [19,20] This relatively simple approach does not damage GaN, MacEtch, was studied to etch. It is difficult to etchforce, wide-bandgap conventional be- to directly decomposed An external such as aGaN lightusing or power source,MacEtch is required cause electron–hole pairs cannot be directly decomposed. An external force, such as a light drive the anode decomposition of the semiconductor [21,22].

Materials and Methods

Selection

Effect

Conclusions