J. Semicond. > 2016, Volume 37 > Issue 2 > 026001
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SEMICONDUCTOR TECHNOLOGY

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

Yiyu Wang1, 2, Zhaoyang Peng1, Huajun Shen1, , Chengzhan Li2, Jia Wu2, Yachao Tang1, Yanli Zhao2, Ximing Chen2, Kean Liu2 and Xinyu Liu1

+ Author Affiliations

 Corresponding author: Huajun Shen, shenhuajun@ime.ac.cn

DOI: 10.1088/1674-4926/37/2/026001

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Abstract: 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, Δ VFB, 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 Δ VFB 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.

Key words: SiO2/SiC interface, NO annealing, forming gas annealing, density of interface states



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图 1.  4H-SiC MOS capacitor and its fabrication process flow. The post-oxidation treatments for each sample are also shown.

Fig.1.


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Fig2.  (Color online) (a) Typical capacitance–voltage and (b) conductance–voltage characteristics of the MOS capacitors measured at different frequencies (parallel mode).

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Fig3.  Equivalent circuit for a MOS capacitor, where Cox, CD, CIT, and GPIT are the oxide capacitance, the semiconductor capacitance, the interface-state capacitance, and the interface-state conductance, respectively.

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Fig4.  The parallel-mode capacitance measured at different frequencies for SiC-MOS capacitors underwent various fabrication conditions. The measurements are performed at room temperature.

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Fig5.  Interface-state conductance against frequency for SiC-MOS capacitors under various fabrication conditions. The measurements are performed at room temperature.

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Fig6.  (a) The densities of interface states and (b) time constant for the as-oxidized sample and FGA sample. The values were extracted from conductance measurements at room temperature.

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Fig7.  The parallel-mode capacitance for the NO & FGA sample measured at low temperatures.

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Fig8.  Interface-state conductance against frequency for the NO & FGA sample measured at low temperatures.

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Fig9.  The density of interface-states for SiC-MOS capacitors under various fabrication conditions.

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Fig10.  Interface-state conductance against temperature for the NO & FGA sample measured at 100 kHz. Multiple lines show the results measured at different gate voltages.

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Fig11.  XPS spectra of N 1s for the SiO2/SiC structures under various fabrication conditions.

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Fig12.  Flatband voltage shift extracted from C–V characteristics as a function of the maximum accumulation voltage of C–V sweep.

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    Received: 22 May 2015 Revised: Online: Published: 01 February 2016

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      Article Navigation >  Journal of Semiconductors  > 2016  >  37(2): 026001
      Yiyu Wang, Zhaoyang Peng, Huajun Shen, Chengzhan Li, Jia Wu, Yachao Tang, Yanli Zhao, Ximing Chen, Kean Liu, Xinyu Liu. Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements[J]. Journal of Semiconductors, 2016, 37(2): 026001. doi: 10.1088/1674-4926/37/2/026001 ****Y Y Wang, Z Y Peng, H J Shen, C Z Li, J Wu, Y C Tang, Y L Zhao, X M Chen, K A Liu, X Y Liu. Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements[J]. J. Semicond., 2016, 37(2): 026001. doi: 10.1088/1674-4926/37/2/026001.
      Citation:
      Yiyu Wang, Zhaoyang Peng, Huajun Shen, Chengzhan Li, Jia Wu, Yachao Tang, Yanli Zhao, Ximing Chen, Kean Liu, Xinyu Liu. Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements[J]. Journal of Semiconductors, 2016, 37(2): 026001. doi: 10.1088/1674-4926/37/2/026001 ****
      Y Y Wang, Z Y Peng, H J Shen, C Z Li, J Wu, Y C Tang, Y L Zhao, X M Chen, K A Liu, X Y Liu. Characterization of the effects of nitrogen and hydrogen passivation on SiO2/4H-SiC interface by low temperature conductance measurements[J]. J. Semicond., 2016, 37(2): 026001. doi: 10.1088/1674-4926/37/2/026001.
      shu

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

      DOI: 10.1088/1674-4926/37/2/026001
      • 1.

        Microwave Device and IC Department, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China

      • 2.

        Zhuzhou CSR Times Electric Co., Ltd, Zhuzhou 412001, China

      Funds:

      Project supported by the National Natural Science Foundation of China (Nos. 61106080, 61275042) and the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2013ZX02305).

      More Information
      • Corresponding author: shenhuajun@ime.ac.cn
      • Received Date: 2015-05-22
      • Accepted Date: 2015-09-01
      • Published Date: 2016-01-25

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