The effects of nitrogen plasma on reactive-ion etching induced damage in GaN

Abstract

Lightly doped n-GaN samples were etched with reactive ion etching (RIE) in BCl3/Cl2/Ar and BCl3/Cl2/N2 plasmas. Replacing the argon by nitrogen in the plasma chemistry resulted in better etch rates, and in addition reduced etch damage for relatively low values of the plasma power. By treating the samples in a nitrogen plasma following etching, we dramatically reduced surface damage, as determined from Schottky IV characteristics measurements. Specifically, the reverse breakdown voltages returned to 70% to that measured from control diode samples. Further, x-ray photoelectron spectroscopy analysis showed that the post-etch nitrogen step decreased the Ga/N ratio. These results suggest that much of the damage induced by RIE plasma etching comes from a nitrogen loss mechanism.

Interface trap states in Al2O3/AlGaN/GaN structure induced by inductively coupled plasma etching of AlGaN surfaces

“…Since the interface quality significantly affects the transistor performance, plasma‐assisted dry etching to form the recessed gate region and the subsequent formation of an insulator–semiconductor interface are critical steps for fabricating such devices. It has been reported that plasma‐assisted etching degrades the electrical and optical properties of GaN and AlGaN surfaces . Tang et al examined the SiO 2 /n‐GaN‐based capacitors and field‐effect transistors (FETs) fabricated on a Cl 2 ‐based inductively coupled plasma (ICP)‐etched GaN surface.…”

Effects of Cl2-Based Inductively Coupled Plasma Etching of AlGaN on Interface Properties of Al2O3/AlGaN/GaN Heterostructures

“…It is known that plasma-assisted etching degrades the electrical and optical properties of GaN and AlGaN surfaces. [9][10][11][12] Tang et al 13) examined the SiO 2 /n-GaN-based capacitors and field-effect transistors (FETs) fabricated on the GaN surfaces etched by a Cl 2 -based inductively coupled plasma (ICP). They showed that ICP etching increased the interface state density and degraded the field-effect mobility of the FET channel.…”

Low-Damage Etching for AlGaN/GaN HEMTs Using Photo-Electrochemical Reactions

“…The dry etching process is commonly used for thinning AlGaN layers, in which the etching is carried out by applying plasma of an appropriate gas mixture containing a chemically reactive element. However, dry-etched surfaces tend to be negatively affected by various types of damage due to the bombardment of reactive ions and radicals [3,4]. These types of damage and defects induce high-density surface and interface states in the forbidden band, which leads to severe operational-stability problems such as gate leakage, current collapse, and Vth instability.…”