Reduction of interface state density in SiC (0001) MOS structures by low-oxygen-partial-pressure annealing

TL;DR

This study demonstrates that low-oxygen-part-pressure annealing effectively reduces interface state density in SiC MOS structures without degrading oxide dielectric properties, offering a promising approach for improved device performance.

Contribution

It introduces low-pO2 annealing as a novel method to lower interface state density in SiC/SiO2 interfaces without causing oxide leakage.

Findings

Interface state density reduced from 6.2×10^12 to 2.4×10^12 eV^{-1}cm^{-2}.

Low-pO2 annealing does not degrade oxide breakdown field (~10.4 MVcm^{-1}).

Pure Ar annealing induces leakage current, unlike low-pO2 annealing.

Abstract

We report that annealing in low-oxygen-partial-pressure (low-p$_{\rm O2}$) ambient is effective in reducing the interface state density (D$_{\rm IT}$) at a SiC (0001)/SiO$_{\rm 2}$ interface near the conduction band edge (E$_{\rm C}$) of SiC. The D$_{\rm IT}$ value at E$_{\rm C}$$-$0.2 eV estimated by a high (1 MHz)-low method is 6.2$\times$10$^{12}$ eV$^{-1}$cm$^{-2}$ in as-oxidized sample, which is reduced to 2.4${\times}$10$^{12}$ eV$^{-1}$cm$^{-2}$ by subsequent annealing in O$_{\rm 2}$ (0.001%) at 1500${}^\circ$C, without interface nitridation. Although annealing in pure Ar induces leakage current in the oxide, low-p$_{\rm O2}$ annealing (p$_{\rm O2}$ = 0.001 - 0.1 %) does not degrade the oxide dielectric property (breakdown field ~ 10.4 MVcm$^{-1}$).