Improved Electrical Properties of SiC-MOS Interfaces by Thermal Oxidation of Plasma Nitrided 4H-SiC(0001) Surfaces
We propose a treatment of nitrogen radical irradiation to 4H-SiC surfaces for improving thermally grown SiO2/SiC interfaces. X-ray photoelectron spectroscopy (XPS) analyses revealed that a 1.7-nm-thick nitride film was formed by nitrogen radical exposure for 30 min and that Si-N bonds were retained after subsequent 10 min oxidation. It was also confirmed by secondary ion mass spectrometry (SIMS) that nitrogen atoms were piled up at the SiO2/SiC interface for the samples fabricated by thermal oxidation for 3 min with nitrogen plasma exposure. The metal-oxide-semiconductor (MOS) capacitors with a thin oxynitride layer formed by nitrogen radical exposure to the SiC surface and subsequent thermal oxidation exhibited excellent capacitance-voltage (C-V) characteristics. The interface state density (Dit) was significantly reduced by nitrogen radical exposure even at the shallow energy level near the conduction band edge. A minimum Dit value of 1.4 × 1011 cm-2eV-1 at Ec – E = 0.44 eV was achieved. Therefore, we can conclude that the treatment of nitrogen radical irradiation to the SiC surface prior to thermal oxidation is a promising method for improving SiC-MOS characteristics.
Anton J. Bauer, Peter Friedrichs, Michael Krieger, Gerhard Pensl, Roland Rupp and Thomas Seyller
Y. Kagei et al., "Improved Electrical Properties of SiC-MOS Interfaces by Thermal Oxidation of Plasma Nitrided 4H-SiC(0001) Surfaces", Materials Science Forum, Vols. 645-648, pp. 507-510, 2010