589-afanas-jap-1999-8292 - SiC/SiO 2 interface-state...

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Unformatted text preview: SiC/SiO 2 interface-state generation by electron injection V. V. Afanas’ev a) and A. Stesmans Department of Physics, University of Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium M. Bassler, G. Pensl, and M. J. Schulz Department of Applied Physics, University of Erlangen – Nu ¨rnberg, Staudtstrasse 7, 91058 Erlangen, Germany C. I. Harris Industrial Microelectronic Center, 16421 Kista, Sweden ~ Received 2 November 1998; accepted for publication 3 March 1999 ! Generation of interface states caused by electron injection in n- and p-type ~ 3C, 4H, 6H ! – SiC/SiO 2 /metal structures was studied using photoinjection methods. The charge trapping in the oxides on SiC was found to be similar to the charging of thermal oxides on Si. However, the generation of interface states in SiC/SiO 2 was larger than in Si/SiO 2 . The interface-state production was found to be enhanced on the C face of SiC as compared to the Si face, and was also found to be enhanced after carbonization of the SiC surface prior to oxidation, which refers to carbon involvement in the SiC/SiO 2 interface-state creation. The observed significant influence of the particular SiC polytype on the interface degradation also suggests an involvement of SiC crystal surface imperfections in the interface-state generation. © 1999 American Institute of Physics. @ S0021-8979 ~ 99 ! 07611-2 # I. INTRODUCTION Charge buildup and generation of interface states are the most important degradation factors in metal–oxide– semiconductor ~ MOS ! devices. They may occur in the course of device fabrication ~ processing-related damage ! or later during device operation causing reliability problems. 1,2 Dur- ing operation, it is the charge injection that leads to the MOS insulator degradation and, ultimately, to breakdown as known for SiO 2 layers on Si. 3,4 The high quality of thermally grown oxides on SiC promises success for SiC MOS devices for high-temperature, high-voltage, and high-power applications. 5–7 However, extreme conditions of operation may accelerate the degradation through enhanced injection of mobile charge carriers ~ electrons and holes ! into the oxide layer: Strongly enhanced hot-electron emission from SiC as compared to Si has been known for nearly four decades. 8 As to the degradation introduced during device fabrication, SiC device processing requires high-dose ion implantation be- cause of the low diffusivity of doping impurities in this semi- conductor, and dry etching because of the lack of liquid etchants compatible with MOS technology. These two as- pects justify a detailed analysis of charge injection effects on the electrical properties of SiC MOS structures. However, to the best of our knowledge such a systematic study has not been performed yet. Particularly missing are data regarding the degradation behavior of p-type SiC MOS structures which are of primary interest for n-channel MOS devices and the comparison of the resistance to degradation of SiC/SiO 2 structures consisting of different SiC polytypes.structures consisting of different SiC polytypes....
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This note was uploaded on 12/10/2009 for the course IF PFIS1200 taught by Professor Antonio during the Spring '09 term at Universidade Federal do Rio de Janeiro.

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589-afanas-jap-1999-8292 - SiC/SiO 2 interface-state...

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