Effects of ultra-low ethylene partial pressure on microstructure and composition of reactively sputter-deposited Ta-C thin films

THIN SOLID FILMS

卷:688

Article

Tanaka, Koichi¹  Aleman, Angel²  Liao, Michael E.¹  Wang, Yekan¹  Goorsky, Mark S.¹  Kodambaka, Suneel¹ 

[1] Univ Calif Los Angeles, Dept Mat Sci & Engn, 410 Westwood Plaza, Los Angeles, CA 90095 USA

[2] Univ Calif Los Angeles, Dept Mech & Aerosp Engn, 410 Westwood Plaza, Los Angeles, CA 90095 USA

关键词: Tantalum carbide;    Reactive magnetron sputtering;    Twinning;    Ultra high vacuum;   

DOI  :  10.1016/j.tsf.2019.137440

来源: Elsevier

【 摘 要 】

We report on the effects of low ethylene (C2H4) partial pressures (6.7 x 10(-5) <= P-c <= 6.7 x 10(-2) Pa) on the composition and microstructure of Ta-C thin films grown on MgO(001) substrates via ultra-high vacuum dc magnetron sputtering of a TaC compound target using 2.7 Pa argon/ethylene gas discharges at 1123 K. The as-deposited layer crystallinity and composition are determined using a combination of X-ray diffraction, transmission electron microscopy coupled with X-ray energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. We find that the layers sputter-deposited in pure Ar (i.e., P-c= 0) and Ar/C2H4 gas mixtures with P-c= 6.7 x 10(-5) Pa are polycrystalline trigonal-structured Ta2C (a= 0.310 nm and c= 0.492 nm). At P-c= 6.7 x 10(-4) Pa, we obtain cubic, 002-textured TaC0.76 (a= 0.442 nm) porous thin film with facetted surface. Interestingly, we also observe 111-oriented twins due to four crystals rotated with respect to each other. Film grown at higher P-c= 6.7 x 10(-2) Pa is relatively dense with smoother surface and composed of a two-phase mixture of nanocrystalline TaC and amorphous carbon. Our results demonstrate compositional and microstructural tunability during sputter-deposition of transition-metal carbide thin films using small amounts of the reactive gas.

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