Enhancement of Minority Carrier Lifetime in Ultra-High Voltage 4H-SiC PiN Diodes by Carbon-Film Annealing

Abstract:

A novel process is developed for minority carrier lifetime enhancement in ultra-high 4H-SiC PiN diodes. It comprises two separate processes. Firstly, the ultra-thick epitaxial grown drift layer (200μm) covered with a protective thin carbon film is subject to a 1500°C high-temperature anneal process in Ar atmosphere for 2 hours. Secondly, a surface passivation process is adopted to reduce the surface recombination rate. μ-PCD tests show that after high-temperature anneal, the thick drift layer shows a minority carrier lifetime increase to about 1.6 μs. PiN diodes based on the novel process are fabricated and their electric characteristics are measured. Results show a low specific on-resistance of 16.3 mΩ·cm² at 25°C and 14 mΩ·cm² at 125 °C. Compared with simulation results, it is shown that its effective minority carrier lifetime increase to about 5μs .Our study demonstrates that the developed novel process is effective in minority carrier lifetime enhancement in ultra-voltage 4H-SiC PiN diodes.

• Periodical: Materials Science Forum (Volume 1014)
• Pages: 137-143
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1014.137
• Online since: November 2020
• Authors: Wen Ting Zhang*, Yun Lai An, Yi Ying Zha, Ling Sang, Jing Hua Xia, Fei Yang
• Keywords: 4H-SiC, Carbon-Film Annealing, Carrier Lifetime, PiN Diodes

References

[1] M. Bhatnagar and B. J. Baliga, Comparison of 6H-SiC, 3C-SiC, and Si for power devices, IEEE Trans. Electron Devices 40 (1993) 645-655.

DOI: 10.1109/16.199372

[2] B. J. Baliga, Fundamentals of Power Semiconductor Devices, 2008, pp.203-204.

[3] Y.Sugawara, D.Takayama, K.Asano, R.Singh, J.Palmour and T.Hayashi,12-19kV 4H-SIC pin Diodes with Low Power Loss ,Proceedings of 2001 International Symposium on Power Semiconductor Devices & ICs, Osaka.(2001)27-30.

DOI: 10.1109/ispsd.2001.934552

[4] T. Tawara, H. Tsuchida, S. Izumi, I. Kamata, and K. Izumi,Evaluation of Free Carrier Lifetime and Deep Levels of the Thick 4H-SiC Epilayers. Materials Science Forum. 457-460, (2004) 565.

DOI: 10.4028/www.scientific.net/msf.457-460.565

[5] P.B. Klein, Identification of Defects Limiting the Carrier Lifetime in n-Epitaxial Layers of 4H-SiC, Materials Science Forum Vols. 645-648 (2010) pp.193-198.

DOI: 10.4028/www.scientific.net/msf.645-648.193

[6] Tsunenobu Kimoto, Toru Hiyoshi,Toshihiko Hayashi,and Jun Suda,Impacts of recombination at the surface and in the substrate on carrier lifetimes of n-type 4H–SiC epilayers.Journal of Applied Physics .(2010)083721-1-7.

DOI: 10.1063/1.3498818

[7] Takafumi Okuda1, Tetsuya Miyazawa, Hidekazu Tsuchida, Tsunenobu Kimoto, and Jun Suda,Enhancement of carrier lifetime in lightly Al-doped p-type 4H-SiC epitaxial layers by combination of thermal oxidation and hydrogen annealing.Mater. Res. Soc. Symp. Proc. Vol. 1538(2013).

DOI: 10.7567/apex.7.085501

[8] Naoki Kaji, Hiroki Niwa, Jun Suda and Tsunenobu Kimoto，Ultrahigh-Voltage (> 20 kV) SiC PiN Diodes with a Space-Modulated JTE and Lifetime Enhancement Process via Thermal Oxidation, Materials Science Forum. 778-780, (2014)832-835.

DOI: 10.4028/www.scientific.net/msf.778-780.832

[9] H. M. Ayedh,R. Nipoti,A. Hallen, and B. G. Svensson, Thermodynamic equilibration of the carbon vacancy in 4H-SiC: A lifetime limiting defect, Journal of Applied Physics. (2017) 025701-1-7.

DOI: 10.1063/1.4991815

[10] Lin Cheng, Michael J. O'Loughlin, Alexander V. Suvorov, Edward R. Van Brunt , Albert A. Burk, Anant K. Agarwal, and John W. Palmour, Improvement of Minority Carrier Lifetime in Thick 4H-SiC Epi-layers by Multiple Thermal Oxidations and Anneals , Materials Research Society 1538 (2013)329-333.

DOI: 10.1557/opl.2013.574

[11] Sauvik Chowdhury, Collin Hitchcock, Rajendra P. Dahal, Ishwara B. Bhat and T. Paul Chow, Effect of Carrier Lifetime Enhancement on the Performance of Ultra-High Voltage 4H-SiC PiN Diodes, Lester Eastman Conference on High Performance Device(2016).

DOI: 10.1109/lec.2016.7578925