Evaluation of Surface Roughness and Subsurface Damage of 4H-SiC Processed by Different Finishing Techniques

Abstract:

Article Preview

Single crystal SiC is one of the most attractive semiconductor materials for next generation power device applications. However, it is very difficult to be precisely machined due to its high hardness and chemical inertness. We evaluated the machining characteristics of 4H-SiC using different processes including diamond abrasives lapping, chemical mechanical polishing (CMP) and plasma assisted polishing (PAP). Scratches were introduced through diamond abrasives lapping due to the high hardness of diamond, which resulted in the worsening of surface roughness. A damage layer was observed in the cross-sectional transmission electron microscopy (XTEM) images. A scratch-free surface was obtained through CMP, but it’s not atomically flat since step/terrace structure couldn’t be clearly observed. PAP was newly proposed for the finishing of difficult to machine materials. In PAP, water vapor plasma oxidation and soft abrasive polishing were repeatedly conducted. Ceria which is much softer than SiC was used as the abrasive material. PAP was proved very effective to achieve surfaces out of scratches. Also, due to the low hardness of ceria, no damage layers were introduced. The roughness of PAP processed surface was decreased to about 0.1 nm rms. The surface was also observed by XTEM, which proved an atomically flat surface without crystallographical damage was obtained.

Info:

Periodical:

Key Engineering Materials (Volumes 523-524)

Edited by:

Tojiro Aoyama, Hideki Aoyama, Atsushi Matsubara, Hayato Yoshioka and Libo Zhou

Pages:

19-23

Citation:

H. Deng and K. Yamamura, "Evaluation of Surface Roughness and Subsurface Damage of 4H-SiC Processed by Different Finishing Techniques", Key Engineering Materials, Vols. 523-524, pp. 19-23, 2012

Online since:

November 2012

Export:

Price:

$38.00

[1] H. Kasuga, H. Ohmori, W. Lin, Y. Watanabe, T. Mishima and T. Doi, Efficient and smooth grinding characteristics of mono crystalline 4H-SiC wafer, J. Vac. Sci. Technol. B 27 (2009) 1578.

DOI: https://doi.org/10.1116/1.3056170

[2] X. Chen, X. Xu, J. Li, S. Jiang, L. Ning, Y. Wang, D. Ma, X. Hu and M. Jiang, Surface polishing of 6H-SiC substrates, J. Mater. Sci. Technol. 23 (2007) 430.

[3] L. Zhou, V. Audurier, P. Pirouz, Chemomechanical polishing of silicon carbide, J. Electrochem. Soc. 144 (1997) L161.

DOI: https://doi.org/10.1149/1.1837711

[4] C. L. Neslen, W. C. Mitchel, R. L. Hengehold, Effects of process parameter variations on the removal rate in chemical mechanical polishing of 4H-SiC, J. Electro. Mater. 30 (2001) 1271.

DOI: https://doi.org/10.1007/s11664-001-0111-2

[5] H. Hara, Y. Sano, H. Mimura, K. Arima, A. Kubota, K. Yagi, J. murata and K. Yamauchi, Novel abrasive-free planarization of 4H-SiC (0001) using catalyst, J. Electro. Mater. 35 (2006) L11.

DOI: https://doi.org/10.1007/1-84628-559-3_45

[6] K. Arima, H. Hara, J. Murata, T. Ishida, R. Okamoto, K. Yagi, Y. Sano, H. Mimura and K. Yamauchi, Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst, Appl. Phys. Lett. 90 (2007) 202106.

DOI: https://doi.org/10.1063/1.2739084

[7] S. H. Hong, J. Watanabe and M. Touge, Precision polishing technology of SiC single crystal under ultraviolet-ray irradiation, Int. J. for Manufacturing Science & Technology, 9 (2007) 23.

[8] J. Watanabe, S. H. Hong, K. Yamaguchi, M. Touge and N. Kuroda, Effect of TiO2 and CeO2 particles on SiC semiconductor surfaces polished under ultraviolet-ray irradiation, Advances in Abrasive Technology (ASAAT 2007), Michigan, USA (2007) 91.

[9] K. Yamamura, T. Takiguchi, M. Ueda, A. N. Hattori, N. Zettsu, High-integrity finishing of 4H-SiC (0001) by plasma-assisted polishing, Adv. Mater. Res. 126-128 (2010) 423.

DOI: https://doi.org/10.4028/www.scientific.net/amr.126-128.423

[10] K. Yamamura, T. Takiguchi, M. Ueda, H. Deng, A. N. Hattori, N. Zettsu, Plasma assisted polishing of single crystal SiC for obtaining atomically flat strain-free surface, Ann. CIRP. 60 (2011) 571.

DOI: https://doi.org/10.1016/j.cirp.2011.03.072

[11] H. Deng, T. Takiguchi, M. Ueda, A. N. Hattori, N. Zettsu and K. Yamamura, Damage-free dry polishing of 4H-SiC combined with atmospheric-pressure water vapor plasma oxidation, Jpn. J. Appl. Phys. 50 (2011) 08JG05.

DOI: https://doi.org/10.7567/jjap.50.08jg05