| AVS 61st International Symposium & Exhibition | |
| Advanced Surface Engineering | Tuesday Sessions |
| Session SE+NS+TR-TuM |
| Session: | Nanostructured Thin Films and Coatings |
| Presenter: | Koji Eriguchi, Kyoto University, Japan |
| Authors: | K. Eriguchi, Kyoto University, Japan M. Noma, SHINKO SEIKI CO., LTD., Japan S. Hasegawa, Osaka University, Japan M. Yamashita, Hyogo Prefectural Institute of Tech., Japan K. Ono, Kyoto University, Japan |
| Correspondent: | Click to Email |
Cubic boron nitride (c-BN) has attracted much attention as a hard coating film on cutting tools, owning to its high oxidation resistance and hardness—the second hardest material to diamond. Although various methods of forming c-BN films on various substrates have been proposed, the interface between c-BN and the substrate material was unstable against delamination and oxidation [1] after long-time machining and air exposure. In this study, we propose a novel reactive plasma-assisted coating technique (RePAC) for forming sub-μm-thick BN film directly on crystalline Si substrates, where magnetically-confined high-density Ar/N2 plasma was generated with a stable anodic current to promote the reaction between N radicals and B atoms evaporated onto a Si substrate placed on a sample stage [2]. Controlling substrate bias voltage Vsub in the RePAC, we fabricated various thin-BN/Si structures and identified a correlation among the properties such as mechanical hardness, friction coefficient, leakage current, and dielectric constants. TEM analyses revealed that nano-structures of the BN films were varied from bulk amorphous (a)-BN, layered hexagonal (h)-BN, to c-BN phase in turbostratic (t)-BN domain, in accordance with Vsub (|Vsub|=10–120 V). We speculate that bombardment of incident ions (Ar+ and/or N2+) plays a key role in forming these characteristic features, in addition to stoichiometric N and B contents. Moreover, we clarified the high hardness (> 4000HK, by the Knoop indenter) and the dielectric constant higher than previously-reported values (10–20, by the electrical capacitance measurement) for the present thin c-BN/Si structure with anti-delamination feature after long-time air exposure. The obtained results suggest that the present BN film formed by the RePAC has wide applications not only as a hard coating film but also as a high dielectric-constant layer in electronic devices.
[1] For example, P. B. Mirkarimi et al., Mater. Sci. Engin., R21, 47 (1997).
[2] M. Noma et al., Jpn. J. Appl. Phys. 53, 03DB02 (2014).