SR-XPS analysis of SiO/SiC interfaces formed by thermal oxidation of plasma nitrided SiC surfaces

Kagei, Yusuke*; Kosono, Kohei*; Kutsuki, Katsuhiro*; Yoshigoe, Akitaka ; Teraoka, Yuden; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*

Impact of high-density plasma nitridation of 4H-SiC(0001) surface on thermally grown SiO/SiC interface structure was investigated using synchrotron radiation X-ray photoemission spectroscopy. Surface nitridation was confirmed from Si2p and N1s spectra. Both Si sub-oxide and Si sub-nitride states at SiO/SiC interface was evaluated through deconvolution of Si2p spectra. We found that the amount of Si sub-oxide states increased with the oxidation time. However, the formation of Si sub-oxides was effectively suppressed by the surface nitridation treatment prior to oxidation. Since an interface state density of Al/SiO/SiC MOS capacitor was approximately halved by the surface nitridation treatment, a generation of interface defects was considered to be caused by the Si sub-oxides formation.