Interfacial Treatment of the SiC-SiO2 Interface By Shallow Boron and Barium Multi-Charged Ion Implantation

Abstract

Multicharged ions born and barium ions were used to perform interfacial treatment of the SiC/SiO2 interface. A Q-switched Nd:YAG laser (wavelength λ = 1064 nm, pulse width τ = 7 ns, and fluence F = 135 J/cm2) was used to ablate boron and barium targets to generate multicharged ions. Time-of-flight and three-grid retarding field ion energy analyzer were used to detect the charge state and the ion kinetic energy. Fully stripped boron ions are generated. The ions were deflected by an electrostatic field to separate them from the neutrals. SRIM simulation was used to estimate the ion penetration depth in the SiC substrate. The multicharged ions were used for shallow ion implantation in 4H SiC. The optical bandgap of the 4H SiC was reduced due to boron ion implantation. Several MOSCAP devices were fabricated with combination of boron and barium shallow implantation. High-low C-V measurements were used to characterize the MOSCAPs. Boron implantation affects the flatband voltage significantly, while the effect of barium ion implantation is negligible. Shallow boron implantation in the SiC/SiO2 interface reduces the flatband voltage from 4.5 to 0.04 V.