Structural and electrical characterizations of oxynitride films on solid phase epitaxially grown silicon carbide
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Structural and electrical characterizations of oxynitride films on solid phase epitaxially grown silicon carbide L.K. Bera, W.K. Choi, D. McNeill1, S.K. Ray 2, S. Chatterjee3 and C.K. Maiti3 Microelectronics Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 1 Department of Electronics and Electrical Engineering, The Queen’s University of Belfast, Belfast, U.K. 2 Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur, India. 3 Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur, India. ABSTRACT We have investigated the structural and electrical properties of as-prepared and rapid thermal oxynitride films on C+ implanted solid phase epitaxially grown SiC. The oxynitride was grown using N2O. The C concentration of the samples was estimated to be 1, 2 and 5 at. %. From the infrared spectra, samples with 1 and 2 at. % carbon showed that the carbon was substitutionally incorporated into the silicon. No precipitation of SiC was detected. However, for the 5 at. % C sample, some precipitation was observed as indicated by a broad peak at ~800 cm-1. The oxynitride films showed the Si-O-Si stretching mode at ~1100 cm-1. The shoulder at 980-1067 cm-1 was due to the O-Si-N bond. The peak at 830 cm-1 was due to the Si-N and Si-C bonds and C-O complex vibrational mode was observed at 663 cm-1. Electrical characterization of the oxynitride films was carried out using the MOS capacitor structure. The interface state density was found to range between 5.7×1011 to 3.35×1012 cm-2eV-1 and increased with an increase in the C concentration. The electrical breakdown field was found to be in the range of 57 MV cm-1 and reduced with an increase in C concentration. The charge-to-breakdown value was measured and decreased with an increase in C concentration. INTRODUCTION There has been a substantial interest in alloying group IV elements to silicon so as to tailor the band gap and strain in the heterostructures[1]. The addition of small amount of isoelectronic C atom into silicon provides opportunities to fabricate novel devices by controlling band-gap and strain engineering. As the atomic size of C is 52% smaller than Si, the incorporation of C into substitutional sites in Si creates a tensile strained Si1-xCx layer. Such a tensile strained film on Si causes a large conduction band offset that is suitable for fabricating nchannel metal-oxide-silicon field effect transistors (MOSFETs). The growth of high quality silicon oxide film on Si1-xCx is a crucial step in fabricating MOSFETs on Si1-xCx. In Si integrated circuit technology, high quality nitrided oxides and oxynitrides were reported to provide several advantages as thin gate dielectric when compared to thin thermal oxide. These advantages include improved hot carrier degradation resistance, reduced charge to breakdown value, decreasing radiation induced interface trap, the prevention of boron penetration into oxides of po
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