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Procedia Engineering 32 (2012) 1000 – 1005

1877-7058 © 2012 Published by Elsevier Ltd. doi:10.1016/j.proeng.2012.02.045

Available online at www.sciencedirect.com

I-SEEC2011

Structure and Composition of TiVN Thin Films Deposited by

Reactive DC Magnetron Co-sputtering

T. Deeleard

a

, A. Buranawong

b,c

, A. Choeysuppaket

b,c

,

N. Witit-anun

b,c

, S. Chaiyakun

b,c

, P. Limsuwan

a,c

aDepartment of Physics, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok, 10140, Thailand bVacuum Technology and Thin Film Research Laboratory, Department of Physics, Faculty of Science,

Burapha University, Chonburi, 20131, Thailand

cThailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand

Elsevier use only: Received 30 September 2011; Revised 10 November 2011; Accepted 25 November 2011.

Abstract

Ternary nitride hard coatings are known of excellent wear characteristics which have proved to be successfully transferable to industrial application. This paper presents the structures and compositions of TiVN thin films deposited by Reactive DC Magnetron Co-sputtering technique from a titanium target and a vanadium target alternatively in a mixed Ar/N2 atmosphere. By variation of the vanadium sputtering current, different samples have

been obtained. The sputtering current effects on structures, surface morphologies and element compositions were investigated by X-ray diffraction (XRD), Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) employing Energy-Dispersive X-ray Analysis (EDX). It was found that crystal structures, microstructures, surface morphologies and element compositions of TiVN thin films depended on the deposition parameters. All the samples are composed of TiVN crystal structure (111) (200) and (220) planes and the crystallinity of films changed as a function of vanadium sputtering currents. Roughness and average thickness of the films increased from 2.60 to 7.07 nm and 222.78 to 490.99 nm respectively. The EDX results indicated that the atomic ratio of V to Ti was increased from 0.13 to 1.58.

© 2010 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of I-SEEC2011

Keywords: Vanadium Sputtering Current; TiVN; Reactive DC Magnetron Co-sputtering

* Corresponding author. Tel.: +6-689-145-3465.

E-mail address: prokoong@hotmail.com. Open access under CC BY-NC-ND license.

Open access under CC BY-NC-ND license. Provided by Elsevier - Publisher Connector

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1. Introduction

In recent years, the good properties of multicomponent hard coatings have long been known. Titanium-based ternary hard coatings have been the subject of intensive research because of their excellent physical and chemical properties.TiAlN, TiCrN, TiVN and TiZrN have gained much attention as substitutes for binary nitride coatings with regard to industrial applications involving wear protection, cutting tools and machinery components [1].Some research on this ternary coating film has already been published. Knotek et al. investigated two methods of synthesizing this material: magnetron sputtering and arc ion plating. In both cases,TiVN-coated indexable inserts exhibited excellent performance in turning operations for cutting steels [2,3].Yeung et al. compared TiVN film to other titanium-based ternary nitride films [4,5].

Coatings in the TiVN system were deposited and analysed in order to determine the influence of vanadium in this system. The coatings were deposited using the reactive magnetron co-sputtering process, which permits wide variation in composition, structure and equilibrium conditions.In this paper we report the structure and composition of TiVN films prepared by the reactive magnetron co-sputtering method.



2. Experimental procedure

TiVN films were deposited onto both Si(100) wafers and glass slide without additional heating by reactive magnetron co-sputtering with high purity of Titanium (Ti) and Vanadium (V) target (shown in Fig. 1). The coatings were deposited with two unbalanced, independently controlled magnetrons with a target-substrate working distance of 13 cm. The targets were first sputter cleaned with argon at a pressure

of 5x10-3 mbar for 10 minutes. The base pressure in the chamber was 5x10-5 mbar and the working

pressure was set at 5x10-3 mbar during all depositions. In the deposition process, the Ti target current was

kept at 0.6 A, whereas the V target currents were varied from 0.2 to 1.2 A, consisting of Ar and N2 with a

constant flow rate at 8 sccm and 4 sccm respectively.

The phase structure of the TiVN coatings was determined by X-ray diffractometer (XRD) with a 40-kV operating voltage and Cu KĮ radiation. A scanning program with a 2T scanning rate of 2O min-1

is employed to determine the peak positions of phases occurring in the range of 20O < 2T < 80O.

The thickness and surface morphology of the TiVN films deposited on glass slide substrates are analyzed by the AFM technique (tapping mode) as RMS (root mean square) roughness. The element compositions of coating were examined by scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis system (EDX).

3. Results and discussion

The crystal structure of TiVN films examined by XRD, are shown in Fig. 2. All the samples are composed of TiVN crystal structure (111) (200) and (220) planes which have cubic structure and the crystallinity of films changed as a function of vanadium sputtering currents.Vanadium sputtering current at 0.2 A, XRD pattern show the (200) peak TiVN films of a strong preferred orientation of (200) were reported in other work [6], with increasing vanadium sputtering current to 0.4 A, the intensity of the (200) peak decrease and shift to right of TiN (200). Vanadium sputtering current 0.6 to 1.0 A, XRD pattern shows the (111) peakand the intensity of (111) peak increase and shift to right of TiN (111) when the vanadium sputtering currents were increased. Because of the vanadium ions were smaller in size than the titanium ions and numbers of vanadium ions were increased [7]. At 1.2 A of vanadium sputtering current shows (211) peak which has intensity more (111) and (200) peak and shift to right of TiN (211).

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Fig. 1. Schematic diagram of the reactive magnetron co-sputtering equipment used in this study  20 30 40 50 60 70 80 2T (CuKD) In te ns it y (ar b.u ni t) TiN (200) TiN (220) Iv = 1.2 A Iv = 1.0 A Iv = 0.8 A Iv = 0.6 A Iv = 0.4 A Iv = 0.2 A TiN (111)

Fig. 2. X-ray diffraction patterns at various vanadium sputtering current values (Iv)

S N N S N S N S S N S N MFC MFC Ar N2 Unbalancemagnetron cathode Target Shutter Substrate holder To vacuum pump System DC power supply Target DC power supply Substrate Window Window

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Table 1. Thickness, roughness and composition of the TiVN coatings investigated

Composition (At%) Vanadium sputtering current

(A) Thickness (nm) Roughness (nm) Ti V 0.2 222.79 2.61 8.37 1.08 0.4 250.18 3.73 7.79 2.73 0.6 327.59 4.85 8.53 4.79 0.8 382.32 5.33 8.45 7.34 1.0 454.74 6.45 9.67 10.63 1.2 490.99 7.07 9.26 14.67 (a) (b) (c) (d) (e) (f)

Fig.3. AFM images of surfaces of the TiVN coatings with six different vanadium sputtering currents of (a) 0.2 A, (b) 0.4 A, (c) 0.6 A, (d) 0.8 A, (e) 1.0 A and (f) 1.2 A

Fig. 3 show the AFM images of the surface of the TiVN coatings with six different vanadium sputtering currents of 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 A, respectively. The AFM images indicated that the surface morphology of TiVN coatings considerably depended of vanadium sputtering current. The average surface roughness (RMS) of TiVN coatings was calculated from AFM images of a selected area of 1 x 1 Pm2. The surface morphology of the coatings with lowest current of vanadium sputtering (Fig.3a)

was found to be very smooth (RMS, 2.61 nm) and the thickness of film was less (222.79 nm). Increasing of the vanadium sputtering current up to 1.2, thickness and roughness were increased to 490.99 nm and 7.07 nm respectively (Table 1.). This was believed due to ion bombardment effect which was increase follow to vanadium sputtering currents.

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0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Vanadium sputtering current (A)

El eme nt c on te nt (at%) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Ti V V/Ti V/Ti atomi c r ati o

Fig. 4. Dependence of composition of TiVN films on vanadium sputtering current

The EDX results in Fig. 4 show that by increasing vanadium sputtering current, the ratio of V to Ti content tends to increase while the the Ti content almost stable and the V content to increase. As the vanadium sputtering current increases from 0.2 to 1.2A, the content ratio of V to Ti increases from 0.13 to 1.58 with less change of the Ti content in the range 7.79% to 9.67% in comparison to the increasing V content from 1.08% to 14.67%.

4. Conclusion

TiVN thin films were deposited by Reactive DC Magnetron Co-sputtering on si(100) and glass slides which studies effect of varies vanadium sputtering current. It was found that, all the samples are composed of TiVN crystal structure (111) (200) and (220) planes and the crystallinity of films changed as a function of vanadium sputtering currents. Roughness and average thickness of the films increased from 2.60 to 7.07 nm and 222.78 to 490.99 nm when increased vanadium sputtering current 0.2-1.2 A respectively. The result of EDX indicated that atomic ratio of V to Ti was increased from 0.13 to 1.58.

Acknowledgments

The authors would like to thank Vacuum Technology and Thin Film Research Laboratory, Department of Physics, Faculty of Science, Burapha University for support magnetron co-sputtering system.

References

[1] Lewis DB, Creasey S, Zhou Z, Forsyth JJ, Ehiasarian AP, Hovsepian PEh, Luo Q, Rainforth WM, Munz WD. The effect of (Ti+Al):V ratio on the structure and oxidation behavior of TiAlN/VN nano-scale multilayer coatings. Surf Coat Technol 2004;177–8:252–9.

[2] Knotek O, Löffler F, Krämer G. Multicomponent and multilayer physically vapour deposited coatings for cutting tools. Surf Coat Technol 1993;59:14-0.

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[3] Knotek O, Barimani A, Bosserhoff B, Löffler F. Sturcture and properties of magnetron-sputtered Ti-V-N coating. Thin solid films 1990;193/4:557-564.

[4] Yeung WY, Dub SN, Wuhrer R, Milman YuV. Study of Magnetron Co-Sputtered Nanocrystalline Ternary Niirde Coatings. Science of Sintering 2006;38:211-21.

[5] Hasegawa H. Kimura A. Suzuki T. Microhardness and structural analysis of (Ti,Al)N, (Ti,Cr)N, (Ti,Zi)N and (Ti,V)N films. J Vac Sci Technol 2000;A 18(3):1038-40.

[6] Ouyang JH, Sasaki S. The friction and wear characteristics of cathodic arc ion-plated (V,Ti)N coatings in sliding against alumina ball. Wear 2004;257:708-20.

[7] Ichimiya N, Onishi Y, Tanaka Y. Properties and cutting performance of (Ti,V)N coatings prepared by cathodic arc ion plating. Surf Coat Technol 2005;200:1377-82.

References

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