High-k dielectrics for 4H-silicon carbide: present status and future perspectives

Abstract

Owing to its superior material and electrical properties such as wide bandgap and high breakdown electric field, 4H-silicon carbide (4H-SiC) has shown promise in high power, high temperature, and radiation prone environments. After success in silicon-based technology, metal–insulator–semiconductor (MIS) devices seem to be the obvious choice for 4H-SiC technology as well, due to the availability of its native insulated oxide (SiO₂). However, the use of SiO₂ in 4H-SiC technologies is not an ideal choice due to the poor quality of the SiO₂/4H-SiC interface and the low dielectric constant of SiO₂, which compromise the performance of 4H-SiC devices under high electric fields. Therefore, to exploit the superior properties of 4H-SiC, substantial efforts are being made to overcome this issue by using high-κ dielectrics such as Al₂O₃, AlN, HfO₂, Ta₂O₅, Y₂O₃, ZrO₂, TiO₂, CeO₂, and their combinations in layered stacks. This paper assesses the current status of these dielectrics and their processing in terms of types of dielectric (and their stacks), pre-deposition treatments, deposition methods, post-deposition treatments, and their viability in actual devices. Based on an extensive survey of the structural, electrical, and interfacial characteristics, a future perspective of high-κ dielectrics on 4H-SiC devices is provided.