Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements

• Published in: 半导体学报：英文版 no. 2; pp. 148 - 154
• Main Author: 王弋宇 彭朝阳 申华军 李诚瞻 吴佳 唐亚超 赵艳黎 陈喜明 刘可安 刘新宇
• Format: Journal Article
• Language: English
• Published: 01.02.2016
• Subjects: SiC; SiO2; 低温; 氢钝化; 氮原子; 深能级陷阱; 电导测量; 界面态密度
• ISSN: 1674-4926
• DOI: 10.1088/1674-4926/37/2/026001

We investigate the effects of NO annealing and forming gas （FG） annealing on the electrical properties of a SiO2/SiC interface by low-temperature conductance measurements. With nitrogen passivation, the density of interface states （DIT） is significantly reduced in the entire energy range, and the shift of flatband voltage, AVFB, is effectively suppressed to less than 0.4 V. However, very fast states are observed after NO annealing and the response frequencies are higher than 1 MHz at room temperature. After additional FG annealing, the DIT and AVFB are further reduced. The values of the DIT decrease to less than 1011 cm-2 eV- 1 for the energy range of Ec - ET 〉/0.4 eV. It is suggested that the fast states in shallow energy levels originated from the N atoms accumulating at the interface by NO annealing. Though FG annealing has a limited effect on these shallow traps, hydrogen can terminate the residual Si and C dangling bonds corresponding to traps at deep energy levels and improve the interface quality further. It is indicated that NO annealing in conjunction with FG annealing will be a better post-oxidation process method for high performance SiC MOSFETs.