Low-Damage and Self-Limiting (Al)GaN Etching Process through Atomic Layer Etching Using O2 and BCl3 Plasma

Il-Hwan Hwang,Kwang-Seok Seo,Ho-Young Cha

doi:10.3390/coatings11030268

Il-Hwan Hwang, Kwang-Seok Seo + Show 1 more

Open Access

https://doi.org/10.3390/coatings11030268

Copy DOI

Journal: Coatings	Publication Date: Feb 25, 2021
Citations: 14	License type: CC BY 4.0

Affiliation: Seoul National University, Hongik University

Abstract

This paper reports on the use of low-damage atomic layer etching (ALE) performed using O2 and BCl3 plasma for etching (Al)GaN. The proposed ALE process led to excellent self-limiting etch characteristics with a low direct current (DC) self-bias, which resulted in a high linearity between the etching depth and number of cycles. The etching damage was evaluated using several methods, including atomic force microscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy, and the I–V properties of the recessed Schottky diodes were compared with those of digital etching performed using O2 plasma and HCl solution. The electrical characteristics of the recessed Schottky diode fabricated using the proposed ALE process were superior to those of the diodes fabricated using the conventional digital etching process. Moreover, the ALE process yielded a higher PL intensity and N/(Al + Ga) ratio of the etched AlGaN surface, along with a smoother etched surface.

Highlights

Process through Atomic LayerGaN-based high electron mobility transistors have been developed for use in highfrequency amplifiers and high-voltage power switching applications owing to their high breakdown voltage, large bandgap, and high electron carrier velocity [1]
In this study, we report on an atomic layer etching (ALE) process performed using O2 and BCl3 plasma, which exhibits a low direct current (DC) self-bias and self-limiting characteristics
The zero-bias barrier heights were 0.81 and 0.72 eV for the diodes fabricated using the ALE and digital etching, respectively, and a lower reverse current of 4.8 nA at −2 V occurred at the ALE diodes

Summary

Introduction

Process through Atomic LayerGaN-based high electron mobility transistors have been developed for use in highfrequency amplifiers and high-voltage power switching applications owing to their high breakdown voltage, large bandgap, and high electron carrier velocity [1]. Conventional plasma-etching methods, such as reactive ion etching (RIE) and inductively coupled plasma (ICP)-RIE [8–11], are still being widely used, a digital etching process involving the O2 plasma oxidation of (Al)GaN in conjunction with HCl:H2 O solution-based oxide removal has received considerable attention owing to the associated low etching damage and easy control of the recess depth. This process is labor-intensive due to the combination of the plasma oxidation and wet etching processes and involves a low etch rate [12]. To exploit the advantages of the ALE process, the process conditions must be optimized to minimize the plasma-induced etching damage and to attain self-limiting characteristics to precisely control the etch depth

Methods

Results

Conclusion