Influence of vacuum annealing on interface properties of SiC (0001) MOS structures

Abstract

We investigated the influence of vacuum annealing on interface properties of silicon carbide (SiC) metal-oxide-semiconductor (MOS) structures. For as-oxidized and nitric oxide (NO)-annealed samples, the interface state density ($D_{\mathrm{it}}$) near the conduction band edge ($E_{\mathrm{C}}$) of SiC did not increase by subsequent vacuum annealing. For phosphoryl chloride (POCl${}_3$)-annealed samples, in contrast, $D_{\mathrm{it}}$ at $E_{\mathrm{C}}-0.2$ eV increased from $1.3\times 10^{10}$ to $2.2\times 10^{12}$ cm${}^{-2}$eV${}^{-1}$ by the vacuum annealing, and the channel mobility of MOS field effect transistors (MOSFETs) decreased from 109 to 44 cm${}^2$V${}^{-1}$s${}^{-1}$. Mechanism of the observed increase in $D_{\mathrm{it}}$ was discussed based on the results of secondary ion mass spectrometry measurement.

12 pages, 3 figures