Effect of surface preparation and interfacial layer on the quality of SiO2/GaN interfaces

Abstract

In this work, SiO2/GaN MOS structures have been fabricated using Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition (ECR-PECVD) for deposition of silicon dioxide (SiO2) at low temperature (300 °C) on N-type, NID and P-type GaN epitaxial layers. Surface preparation involving chemical, UV-Ozone oxidation and oxygen plasma oxidation have been investigated by XPS analysis of the GaN surfaces prior to SiO2 deposition. The association of UV ozone and plasma oxidation allows a complete removal of carbon contamination and has a huge beneficial effect on the quality of the SiO2/GaN interface. Electrical C-V characterizations put into evidence the improved quality of the SiO2/GaN interface with a low interface trap density of 1010 cm−2 eV−1. The advantage of this soft interface treatment is thus specially observed for the N-type samples without annealing step, whereas improvements are still needed in the case of NID and P-type samples.

Chemical Treatment of Low-k Dielectric Surfaces for Patterning of Thin Solid Films in Microelectronic Applications

“… Silylation is used in many instances to render silica surfaces hydrophobic, which it does by capping the silanol groups (Si–OH) present on the surface. , Because those moieties act as nucleation sites during the chemical deposition of solid films, silylation can also be used to inhibit ALD processes . Regarding radiation with ultraviolet (UV) light while in the presence of ozone, this is known to oxidize organic matter, and is therefore commonly used to clean solid surfaces. − In our study, we were able to demonstrate that mild UV/O 3 treatments are capable of removing the silylation agents from SiO 2 films and to reinstate their reactivity toward ALD . A combination of both steps can therefore afford the selective activation and deactivation of ALD processes on silicon oxide surfaces .…”

Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

“…An optimized process for reduced interface state density at the oxide/n-type semiconductor interface is unlikely to be directly transferrable to a p-type GaN device. In fact, reference [ 129 ] demonstrates that for similar interface preparation steps for each GaN doping type (n-type, p-type and unintentionally doped), the optimization of the surface preparation is strongly dependent on the GaN doping type.…”

“…The high-low frequency method or conductance method, which do not require a theoretical profile to compare with the measured profile, can be considered to reduce the uncertainty associated with doping concentration in CV characterizations of the GaN MOS system. However, due to high series resistance and system noise, very few quasi-static or low (below 100 Hz) frequency CV profiles have been reported to date [ 94 ] and the conductance method can only measure interface states with short emission times [ 85 ]. The method developed for SiC—a photo-assisted CV measurement—was used by Wu et al on GaN [ 95 ] and measurements taken at varying temperatures were demonstrated in references [ 96 ] and [ 97 ].…”

Investigation of the GaN/Al2O3 Interface by First Principles Calculations

“…There are many candidates for dielectric films of GaN MOSFETs, such as Ga 2 O 3 , SiO 2 , Al 2 O 3 , Gd 2 O 3 , HfO 2 , and AlN . In general, a material with large conduction‐band offset is suitable for the dielectric films since it suppresses the leakage current.…”