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

Abstract

We report that annealing in low-oxygen-partial-pressure (low-p${}_{O2}$) ambient is effective in reducing the interface state density (D${}_{\mathrm{IT}}$) at a SiC (0001)/SiO${}_2$ interface near the conduction band edge (E${}_{\mathrm{C}}$) of SiC. The D${}_{\mathrm{IT}}$ value at E${}_{\mathrm{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${}_2$ (0.001%) at 1500${}^{\circ }$C, without interface nitridation. Although annealing in pure Ar induces leakage current in the oxide, low-p${}_{O2}$ annealing (p${}_{O2}$ = 0.001 - 0.1 %) does not degrade the oxide dielectric property (breakdown field ~ 10.4 MVcm${}^{-1}$).

15 pages, 5 figures