Damage-free highly efficient plasma-assisted polishing of a 20-mm square large mosaic single crystal diamond substrate

Nian Liu; Kohki Sugawara; Naoya Yoshitaka; Hideaki Yamada; Daisuke Takeuchi; Yuko Akabane; Kenichi Fujino; Kentaro Kawai; Kenta Arima; Kazuya Yamamura

doi:10.1038/s41598-020-76430-6

Damage-free highly efficient plasma-assisted polishing of a 20-mm square large mosaic single crystal diamond substrate

Sci Rep. 2020 Nov 10;10(1):19432. doi: 10.1038/s41598-020-76430-6.

Authors

Affiliations

¹ Department of Precision Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
² TDC Corporation, 24-15 Chojamae, Aza, Iidoi, Rifucho, Miyagi District, Miyagi, 981-0113, Japan.
³ Diamond Material Team, Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midoriga-oka, Ikeda, Osaka, 563-8577, Japan.
⁴ Department of Precision Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan. yamamura@prec.eng.osaka-u.ac.jp.

Abstract

Plasma-assisted polishing (PAP) as a damage-free and highly efficient polishing technique has been widely applied to difficult-to-machine wide-gap semiconductor materials such as 4H-SiC (0001) and GaN (0001). In this study, a 20-mm square large mosaic single crystal diamond (SCD) substrate synthesized by microwave plasma chemical vapor deposition (CVD) was polished by PAP. Argon-based plasma containing oxygen was used in PAP to modify the surface of quartz glass polishing plate, and a high material removal rate (MRR) of 13.3 μm/h was obtained. The flatness of SCD polished by PAP measured by an interferometer was 0.5 μm. The surface roughness measured by both scanning white light interferometer (SWLI) (84-μm square) and atomic force microscope (AFM) (5-μm square) was less than 0.5 nm Sq. The micro-Raman spectroscopy measurement results of mosaic SCD substrate processed by PAP showed that residual stress and non-diamond components on the surface after PAP processing were below the detection limit.