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Synthesis and properties of BN:C films deposited by a dual-ion beam sputtering method
Diamond and Related Materials 12 (2003) 1122–1126
Synthesis and properties of BN:C films deposited by a dual-ion beam sputtering method S. Kurookaa,b,*, T. Ikedaa,b, M. Suzukia, A. Tanakac a
Joint Research Consortium of FCT, JFCC, cyo Research Center for Advanced Carbon Materials, AIST, Tsukuba Central 5, Tsukuba, Ibaraki 305-8565, Japan b Ion Engineering Research Institute Corporation, 2-8-1, Tsuda-Yamate, Hirakata, Osaka 573-0128, Japan c Research Center for Advanced Carbon Materials, AIST, Tsukuba Central 5, 1-1, Higashi, Tsukuba, Ibaraki 305-8565, Japan
Abstract Boron nitride films with carbon added (BN:C) were deposited on Si (1 0 0) substrates by a dual-ion beam sputtering deposition method. The BN:C films were analyzed by electron spectroscopy for chemical analysis and a Fourier transform infrared spectroscopy. In addition, a nano-indentation method was used to measure the hardness of the films. Internal stress was estimated by the bending-beam method. With an increase in the C content, the content of the cubic phase in BN:C films was reduced, and the structure of films changed from a cubic phase to a hexagonal phase at more than 13.1 at.% content of the carbon, while the compressive stress of 5.8 GPa and the hardness value of 60 GPa were reduced to 2 GPa and 10 GPa, respectively. Furthermore, the friction coefficient of the films was estimated in dry air, and the BN film with a content of 7.7 at.% carbon showed a lower value of 0.14 compared with 0.17 of the pure-cBN film. 䊚 2003 Elsevier Science B.V. All rights reserved. Keywords: Boron nitride; Ion beam deposition; Friction; Hardness
1. Introduction The cBN film has some outstanding properties similar to those of diamond, such as high-hardness, wearresistance, oxidization resistance and optical transparency. On the other hand, in contrast to diamond, cBN is chemically inert with respect to its reactivity to iron. However, the films usually showed partial peeling from the substrates after deposition due to the large compressive stress. For the relaxation of the internal stress of the films, various techniques were attempted, such as the formation of the interlayer between the cBN film and the substrate w1–3x and of the multilayered structure w4x. However, the intrinsic stress of the cBN was not reduced in either case but, rather, cBN was completely relaxed, as was the film. Therefore, in this study, carbon ions were added to the BN films to relax the cBN film itself. From this, the BN:C films were deposited by the chemical vapor deposition method w5x and by physical *Corresponding author. Tel.yfax: q81-72-859-6651. E-mail addresses: [email protected] (S. Kurooka), [email protected] (S. Kurooka).
vapor deposition methods such as reactive sputtering deposition w6–8x, laser ablation w9x, and ion beamassisted deposition w10,11x. In this experiment to synthesize BN:C films, a dual-ion beam sputtering method was used. FT-IR and electron spectroscopy for chemical analysis (ESCA) measurements were performed. For technical application, it was necessary to investigate the mechanical properties, such as the hardness. Therefore, a nano-indentation measurement was performed. Moreover, a frictional wear test was carried out. 2. Experimental A schematic diagram of the dual-ion beam sputtering apparatus is shown in Fig. 1. It consists of a vacuum chamber, a cryo-pump, four ion sources for sputtering the target materials, and a bucket-type ion source to supply various ions during film growth. For bombarding the film growth, a mixture gas of 30% nitrogen and 70% argon was used. In this study, the bombarding energy was applied at 300 V w4x for all film preparations because it is essential to obtain the cubic phase.
0925-9635/03/$ - see front matter 䊚 2003 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 - 9 6 3 5 Ž 0 2 . 0 0 3 9 8 - 9
S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
Fig. 1. A schematic diagram of a dual-ion beam sputtering apparatus.
The substrate used was a (1 0 0)-face, n-type Si-wafer with the surface polished with hydrofluoric acid to eliminate contamination, such as oxides; the surface was cleaned with ion bombardment from a bombarding ion source before the deposition by applying y1 kV d.c. bias of the acceleration energy to the substrate for 300 s. As sputtering targets, hot-pressed boron (purity: )99.0%) and carbon (purity: 99.999%) were used. The structural investigation of BN:C films was based on Fourier transform infrared spectroscopy with a Nicolet-550 Series 2. Chemical bonding and composition analysis were performed by means of ESCA with a Quantum-2000 using monochromatized Al Ka (1486.6 eV) radiation in a vacuum chamber operating at a pressure lower than 1.3=10y6 Pa. The binding energy of the Au4f core level was taken to be 84.0 eV for energy calibration. The hardness was measured with a nano-indentation unit with a 908 tip on an AFM (Shimazu SPM-1). The tip was calibrated by indenting fused silica at several displacement values. The hardness of BN:C films was estimated from the loadingyunloading curves with the loading value of 100 mN.
compositions of BN:C films were dependent on the starting materials such as B4C target, and kinds of gas fed into the chamber during the deposition, so far the small content of the carbon to keep the cubic phase has been hardly obtained. However, the compositions of films have been provided by excellent control in this study. Fig. 3 shows the hardness and internal stress of the films. The hardness was measured by nano-indentation, and the internal stress was estimated with the bendingbeam method w14x. When the films were deposited on one side of a thin substrate strip clamped at one end, the film stress was calculated using the formula: ss Esds2d y3(1yns)l2df, where the suffix f and s denote the film and substrate, respectively, ssfilm stress, ds deflection of the free end, EsYoung’s modulus, ns Poisson’s ratio, dsthickness, and lslength of the substrate segment. In this measurement, sapphire substrates with values of Ess3.8=1011 Pa, nss0.27, and dss0.1 mm were used. The thickness (f100 nm) and the deflection d of the films were measured by a surface profiler (Tokyo-Seimitsu Corp.). The stylus tracking force was 0.2 mN, and the tracking segment corresponding to l in the above equation was 10 mm. The internal stress of the pure-cBN film was y5.8 GPa, where the negative sign designates a compressive stress. The compressive stress decreased drastically with
3. Results and discussion Fig. 2 shows the FT-IR absorption spectra of the BN:C films as a function of the content of carbon added to the BN films. As can be seen in Fig. 2, a strong broad absorption band and a weaker one were found at 1300 and 780 cmy1, respectively. These absorptions correspond to the BN stretching mode and the B–N–B out-of-plane bending mode, respectively, of the hexagonal BN phase w12x. Approximately 1100 cmy1, a characteristic absorption band was observed, which corresponds to the TO-mode of the cubic B–N phase w13x. With an increase in the content of the carbon, the intensity of the TO-mode decreased, and simultaneously, the hexagonal BN phase increased. When the carbon content exceeded 13.1 at.%, the cubic BN phase disappeared and changed to a hexagonal BN phase. As mentioned above, in the other preparation methods, the
1123
Fig. 2. FT-IR spectra of BN:C films.
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S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
and, in the BN film with a content of 7.7 at.% carbon, its value was 0.14. The friction coefficient continued to increase as the carbon content increased and reached the very high value of 0.32 when the carbon content reached 19.3 at.% without the cubic phase. The addition of carbon to BN films had a remarkable influence on the mechanical properties, such as the hardness, internal stress, and friction coefficients. So, the chemical bonding in the BN:C films was investigated by ESCA measurement. The core-level spectra of B1s, C1s and N1s as a function of the content of carbon are shown in Fig. 5. In the case of the pure-cBN film, the N1s and B1s spectra were obtained as single peaks, and those correspond to 398.1 and 190.5 eV of the B–N bonding w15x, respectively. However, due to the addition of carbon to the BN films, a shoulder peak was observed in the N1s spectra at 398.6 eV, corresponding to the N–C bonding for pyridine w16x, and its intensity remained despite the change in the carbon content. Furthermore, C–B, C–C and C–N bondings corresponding to 283.0 eV w17x, 284.4 and 285.2 eV w16x, respectively, were observed in the C1s spectra. With an increase in carbon content, the intensity of the C1s peak increased, and the peak shifted to the higher binding energy to 284.4 eV. On the other hand, in the B1s spectra, the shoulder peak was observed at 188.4 eV, corresponding to the B–C bonding w17x, and the intensity of the B–C bonding hardly changed, though the intensity of the B–N bonding decreased with the addition of carbon. Therefore, with a small amount of carbon in the BN:C films, from the FT-IR measurement, the hexagonal
Fig. 3. Hardness and internal stress of BN:C films as a function of the carbon content.
a small amount of carbon and then saturated to a constant value of 1.8 GPa, approximately, at more than 34.3 at.% C content of the BN:C films. By adding the carbon to the BN films, no delamination from the substrates occurred in the BN:C films. This change in the internal stress was in good agreement with the behavior of the transmittance corresponding to the cBN TO-mode of the FT-IR measurement; in other words, the quantity of the existence of the cubic phase caused the reduction of the compressive stress. Similarly, the hardness of 60 GPa for the pure-cBN film decreased by adding the carbon and saturated to a constant value of approximately 8 GPa with the disappearance of the cubic phase. Fig. 4 shows the friction coefficients of the BN:C films observed at a normal load equal to 0.1 N; the condition of the wear test is also shown in the same figure. The friction coefficient for the pure-cBN film was 0.17. A small content of 4.7 at.% carbon of the BN film caused the friction coefficient to increase to 0.19,
Fig. 4. Friction coefficients of BN:C films as a function of the carbon content sliding against a SiC ball under a normal load of 0.1 N.
S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
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Fig. 5. XPS spectra for the BN:C films as a function of the carbon content.
BN phase was formed, and the added carbon simultaneously formed a composite with C–N, C–C and C–B bondings. When the content of the carbon was increased even more, the composite was formed primarily with a C–C bonding. Therefore, we assumed that the friction coefficient of a BN film with a small carbon content of 4.7 at.% would increase due to the reduction in hardness. In addition, with a carbon content of 7.7 at.% of BN:C, the film showed a lower value compared with that of the pure-cBN film of the friction coefficient produced by the composite with the C–N, C–C and B–C bondings and the hexagonal B–N phase, which was formed as a lubrication material. Finally, the friction coefficient increased when the hardness decreased. 4. Summary and conclusions In the present study, the aim was to investigate whether or not the addition of carbon to BN films would affect their mechanical and tribological properties. The BN:C films were prepared on Si (1 0 0) substrates by the dual-ion beam sputtering method. The addition of carbon to BN films reduced the internal stress of the films, thereby restraining the delamination of the films from the substrates. More specifically, with a carbon content of 7.7 at.%, the compressive stress was reduced from approximately 5.8 to 3.0 GPa; moreover, the friction coefficient was reduced to a value of 0.14 compared with that of 0.17 in the pure-cBN film. Therefore, we assume that the addition of carbon to BN films is effective for reducing internal stress and improving the friction coefficient.
Acknowledgments The authors would like to thank Dr K. Awazu for the FT-IR measurement at the Institute of Free Electron Laser attached to Osaka University. This work was supported by the Frontier Carbon Technology (FCT) project, which was consigned to Japan Fine Ceramics Center (JFCC) by New Energy and Industrial Technology Development Organization (NEDO). References w1x M. Zeitler, S. Sienz, B. Rauschenbach, J. Vac. Sci. Technol. A 17 (2) (1999) 597. w2x M. Murakawa, S. Watanabe, Surf. Coat. Technol. 43y44 (1990) 128. w3x K. Yamamoto, M. Keunecke, K. Bewilogua, New Diam. Frontier Carbon Technol. 10 (4) (2000) 225. w4x S. Kurooka, T. Ikeda, N. Iwamoto, in: S. Seal, N.B. Dahotre, J.J. Moore, B. Mishra (Eds.), Surface Engineering: In Material Science I, TMS, Warrendale, 2000, p. 357. w5x A.R. Badzian, T. Niemyski, S. Appenheimer, E. Olkusnik, in: F.A. Glaski (Ed.), Proceedings of the Third International Conference on Chemical Vapor Deposition, American Nuclear Society, Hinsdale, IL, 1972, 747. w6x M. Mieno, T. Yoshida, Jpn. J. Appl. Phys. 29 (1990) L1175. w7x A. Schutze, K. Bewilogua, H. Luthje, S. Kouptsidis, S. Jager, ¨ Surf. Coat. Technol. 74–75 (1995) 717. w8x M.P. Johansson, L. Hultman, S. Daaud, et al., Thin Solid Films 287 (1996) 193. w9x M. Dinescu, A. Perrone, A.P. Caricato, et al., Appl. Surf. Sci. 127–129 (1998) 692.
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S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
w10x D.J. Kester, R. Mesier, J. Appl. Phys. 72 (1992) 504. w11x N. Tanabe, M. Iwaki, Diam. Relat. Mater. 2 (1993) 512. w12x T. Takahashi, H. Itoh, A. Takeuchi, J. Crys. Growth 47 (1979) 245. w13x R. Geick, C.H. Perry, Phys. Rev. 146 (1966) 543. w14x H.K. Pulker, Proceedings of the Eighth Inter. Conf. on Vac. Metallurgy, Linz, 1985, 115.
w15x K. Hamrin, G. Johansson, U. Gelious, C. Nordling, K. Siegbahn, Phys. Scr. 1 (1970) 277. w16x C.D. Wagner, W.M. Riggs, L.E. Davis, J.F. Moulder, G.E. Muilenberg, Handbook of X-ray Photoelectron Spectroscopy, Perkin Elmer, Physical Electronics Division, Eden Prairie, MN, 1979. w17x H. Kunzli, ¨ P. Gantenbein, R. Steiner, P. Oelhafen, Fresenius J. Anal. Chem. 346 (1993) 41.
Synthesis and properties of BN:C films deposited by a dual-ion beam sputtering method S. Kurookaa,b,*, T. Ikedaa,b, M. Suzukia, A. Tanakac a
Joint Research Consortium of FCT, JFCC, cyo Research Center for Advanced Carbon Materials, AIST, Tsukuba Central 5, Tsukuba, Ibaraki 305-8565, Japan b Ion Engineering Research Institute Corporation, 2-8-1, Tsuda-Yamate, Hirakata, Osaka 573-0128, Japan c Research Center for Advanced Carbon Materials, AIST, Tsukuba Central 5, 1-1, Higashi, Tsukuba, Ibaraki 305-8565, Japan
Abstract Boron nitride films with carbon added (BN:C) were deposited on Si (1 0 0) substrates by a dual-ion beam sputtering deposition method. The BN:C films were analyzed by electron spectroscopy for chemical analysis and a Fourier transform infrared spectroscopy. In addition, a nano-indentation method was used to measure the hardness of the films. Internal stress was estimated by the bending-beam method. With an increase in the C content, the content of the cubic phase in BN:C films was reduced, and the structure of films changed from a cubic phase to a hexagonal phase at more than 13.1 at.% content of the carbon, while the compressive stress of 5.8 GPa and the hardness value of 60 GPa were reduced to 2 GPa and 10 GPa, respectively. Furthermore, the friction coefficient of the films was estimated in dry air, and the BN film with a content of 7.7 at.% carbon showed a lower value of 0.14 compared with 0.17 of the pure-cBN film. 䊚 2003 Elsevier Science B.V. All rights reserved. Keywords: Boron nitride; Ion beam deposition; Friction; Hardness
1. Introduction The cBN film has some outstanding properties similar to those of diamond, such as high-hardness, wearresistance, oxidization resistance and optical transparency. On the other hand, in contrast to diamond, cBN is chemically inert with respect to its reactivity to iron. However, the films usually showed partial peeling from the substrates after deposition due to the large compressive stress. For the relaxation of the internal stress of the films, various techniques were attempted, such as the formation of the interlayer between the cBN film and the substrate w1–3x and of the multilayered structure w4x. However, the intrinsic stress of the cBN was not reduced in either case but, rather, cBN was completely relaxed, as was the film. Therefore, in this study, carbon ions were added to the BN films to relax the cBN film itself. From this, the BN:C films were deposited by the chemical vapor deposition method w5x and by physical *Corresponding author. Tel.yfax: q81-72-859-6651. E-mail addresses: [email protected] (S. Kurooka), [email protected] (S. Kurooka).
vapor deposition methods such as reactive sputtering deposition w6–8x, laser ablation w9x, and ion beamassisted deposition w10,11x. In this experiment to synthesize BN:C films, a dual-ion beam sputtering method was used. FT-IR and electron spectroscopy for chemical analysis (ESCA) measurements were performed. For technical application, it was necessary to investigate the mechanical properties, such as the hardness. Therefore, a nano-indentation measurement was performed. Moreover, a frictional wear test was carried out. 2. Experimental A schematic diagram of the dual-ion beam sputtering apparatus is shown in Fig. 1. It consists of a vacuum chamber, a cryo-pump, four ion sources for sputtering the target materials, and a bucket-type ion source to supply various ions during film growth. For bombarding the film growth, a mixture gas of 30% nitrogen and 70% argon was used. In this study, the bombarding energy was applied at 300 V w4x for all film preparations because it is essential to obtain the cubic phase.
0925-9635/03/$ - see front matter 䊚 2003 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 - 9 6 3 5 Ž 0 2 . 0 0 3 9 8 - 9
S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
Fig. 1. A schematic diagram of a dual-ion beam sputtering apparatus.
The substrate used was a (1 0 0)-face, n-type Si-wafer with the surface polished with hydrofluoric acid to eliminate contamination, such as oxides; the surface was cleaned with ion bombardment from a bombarding ion source before the deposition by applying y1 kV d.c. bias of the acceleration energy to the substrate for 300 s. As sputtering targets, hot-pressed boron (purity: )99.0%) and carbon (purity: 99.999%) were used. The structural investigation of BN:C films was based on Fourier transform infrared spectroscopy with a Nicolet-550 Series 2. Chemical bonding and composition analysis were performed by means of ESCA with a Quantum-2000 using monochromatized Al Ka (1486.6 eV) radiation in a vacuum chamber operating at a pressure lower than 1.3=10y6 Pa. The binding energy of the Au4f core level was taken to be 84.0 eV for energy calibration. The hardness was measured with a nano-indentation unit with a 908 tip on an AFM (Shimazu SPM-1). The tip was calibrated by indenting fused silica at several displacement values. The hardness of BN:C films was estimated from the loadingyunloading curves with the loading value of 100 mN.
compositions of BN:C films were dependent on the starting materials such as B4C target, and kinds of gas fed into the chamber during the deposition, so far the small content of the carbon to keep the cubic phase has been hardly obtained. However, the compositions of films have been provided by excellent control in this study. Fig. 3 shows the hardness and internal stress of the films. The hardness was measured by nano-indentation, and the internal stress was estimated with the bendingbeam method w14x. When the films were deposited on one side of a thin substrate strip clamped at one end, the film stress was calculated using the formula: ss Esds2d y3(1yns)l2df, where the suffix f and s denote the film and substrate, respectively, ssfilm stress, ds deflection of the free end, EsYoung’s modulus, ns Poisson’s ratio, dsthickness, and lslength of the substrate segment. In this measurement, sapphire substrates with values of Ess3.8=1011 Pa, nss0.27, and dss0.1 mm were used. The thickness (f100 nm) and the deflection d of the films were measured by a surface profiler (Tokyo-Seimitsu Corp.). The stylus tracking force was 0.2 mN, and the tracking segment corresponding to l in the above equation was 10 mm. The internal stress of the pure-cBN film was y5.8 GPa, where the negative sign designates a compressive stress. The compressive stress decreased drastically with
3. Results and discussion Fig. 2 shows the FT-IR absorption spectra of the BN:C films as a function of the content of carbon added to the BN films. As can be seen in Fig. 2, a strong broad absorption band and a weaker one were found at 1300 and 780 cmy1, respectively. These absorptions correspond to the BN stretching mode and the B–N–B out-of-plane bending mode, respectively, of the hexagonal BN phase w12x. Approximately 1100 cmy1, a characteristic absorption band was observed, which corresponds to the TO-mode of the cubic B–N phase w13x. With an increase in the content of the carbon, the intensity of the TO-mode decreased, and simultaneously, the hexagonal BN phase increased. When the carbon content exceeded 13.1 at.%, the cubic BN phase disappeared and changed to a hexagonal BN phase. As mentioned above, in the other preparation methods, the
1123
Fig. 2. FT-IR spectra of BN:C films.
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S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
and, in the BN film with a content of 7.7 at.% carbon, its value was 0.14. The friction coefficient continued to increase as the carbon content increased and reached the very high value of 0.32 when the carbon content reached 19.3 at.% without the cubic phase. The addition of carbon to BN films had a remarkable influence on the mechanical properties, such as the hardness, internal stress, and friction coefficients. So, the chemical bonding in the BN:C films was investigated by ESCA measurement. The core-level spectra of B1s, C1s and N1s as a function of the content of carbon are shown in Fig. 5. In the case of the pure-cBN film, the N1s and B1s spectra were obtained as single peaks, and those correspond to 398.1 and 190.5 eV of the B–N bonding w15x, respectively. However, due to the addition of carbon to the BN films, a shoulder peak was observed in the N1s spectra at 398.6 eV, corresponding to the N–C bonding for pyridine w16x, and its intensity remained despite the change in the carbon content. Furthermore, C–B, C–C and C–N bondings corresponding to 283.0 eV w17x, 284.4 and 285.2 eV w16x, respectively, were observed in the C1s spectra. With an increase in carbon content, the intensity of the C1s peak increased, and the peak shifted to the higher binding energy to 284.4 eV. On the other hand, in the B1s spectra, the shoulder peak was observed at 188.4 eV, corresponding to the B–C bonding w17x, and the intensity of the B–C bonding hardly changed, though the intensity of the B–N bonding decreased with the addition of carbon. Therefore, with a small amount of carbon in the BN:C films, from the FT-IR measurement, the hexagonal
Fig. 3. Hardness and internal stress of BN:C films as a function of the carbon content.
a small amount of carbon and then saturated to a constant value of 1.8 GPa, approximately, at more than 34.3 at.% C content of the BN:C films. By adding the carbon to the BN films, no delamination from the substrates occurred in the BN:C films. This change in the internal stress was in good agreement with the behavior of the transmittance corresponding to the cBN TO-mode of the FT-IR measurement; in other words, the quantity of the existence of the cubic phase caused the reduction of the compressive stress. Similarly, the hardness of 60 GPa for the pure-cBN film decreased by adding the carbon and saturated to a constant value of approximately 8 GPa with the disappearance of the cubic phase. Fig. 4 shows the friction coefficients of the BN:C films observed at a normal load equal to 0.1 N; the condition of the wear test is also shown in the same figure. The friction coefficient for the pure-cBN film was 0.17. A small content of 4.7 at.% carbon of the BN film caused the friction coefficient to increase to 0.19,
Fig. 4. Friction coefficients of BN:C films as a function of the carbon content sliding against a SiC ball under a normal load of 0.1 N.
S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
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Fig. 5. XPS spectra for the BN:C films as a function of the carbon content.
BN phase was formed, and the added carbon simultaneously formed a composite with C–N, C–C and C–B bondings. When the content of the carbon was increased even more, the composite was formed primarily with a C–C bonding. Therefore, we assumed that the friction coefficient of a BN film with a small carbon content of 4.7 at.% would increase due to the reduction in hardness. In addition, with a carbon content of 7.7 at.% of BN:C, the film showed a lower value compared with that of the pure-cBN film of the friction coefficient produced by the composite with the C–N, C–C and B–C bondings and the hexagonal B–N phase, which was formed as a lubrication material. Finally, the friction coefficient increased when the hardness decreased. 4. Summary and conclusions In the present study, the aim was to investigate whether or not the addition of carbon to BN films would affect their mechanical and tribological properties. The BN:C films were prepared on Si (1 0 0) substrates by the dual-ion beam sputtering method. The addition of carbon to BN films reduced the internal stress of the films, thereby restraining the delamination of the films from the substrates. More specifically, with a carbon content of 7.7 at.%, the compressive stress was reduced from approximately 5.8 to 3.0 GPa; moreover, the friction coefficient was reduced to a value of 0.14 compared with that of 0.17 in the pure-cBN film. Therefore, we assume that the addition of carbon to BN films is effective for reducing internal stress and improving the friction coefficient.
Acknowledgments The authors would like to thank Dr K. Awazu for the FT-IR measurement at the Institute of Free Electron Laser attached to Osaka University. This work was supported by the Frontier Carbon Technology (FCT) project, which was consigned to Japan Fine Ceramics Center (JFCC) by New Energy and Industrial Technology Development Organization (NEDO). References w1x M. Zeitler, S. Sienz, B. Rauschenbach, J. Vac. Sci. Technol. A 17 (2) (1999) 597. w2x M. Murakawa, S. Watanabe, Surf. Coat. Technol. 43y44 (1990) 128. w3x K. Yamamoto, M. Keunecke, K. Bewilogua, New Diam. Frontier Carbon Technol. 10 (4) (2000) 225. w4x S. Kurooka, T. Ikeda, N. Iwamoto, in: S. Seal, N.B. Dahotre, J.J. Moore, B. Mishra (Eds.), Surface Engineering: In Material Science I, TMS, Warrendale, 2000, p. 357. w5x A.R. Badzian, T. Niemyski, S. Appenheimer, E. Olkusnik, in: F.A. Glaski (Ed.), Proceedings of the Third International Conference on Chemical Vapor Deposition, American Nuclear Society, Hinsdale, IL, 1972, 747. w6x M. Mieno, T. Yoshida, Jpn. J. Appl. Phys. 29 (1990) L1175. w7x A. Schutze, K. Bewilogua, H. Luthje, S. Kouptsidis, S. Jager, ¨ Surf. Coat. Technol. 74–75 (1995) 717. w8x M.P. Johansson, L. Hultman, S. Daaud, et al., Thin Solid Films 287 (1996) 193. w9x M. Dinescu, A. Perrone, A.P. Caricato, et al., Appl. Surf. Sci. 127–129 (1998) 692.
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S. Kurooka et al. / Diamond and Related Materials 12 (2003) 1122–1126
w10x D.J. Kester, R. Mesier, J. Appl. Phys. 72 (1992) 504. w11x N. Tanabe, M. Iwaki, Diam. Relat. Mater. 2 (1993) 512. w12x T. Takahashi, H. Itoh, A. Takeuchi, J. Crys. Growth 47 (1979) 245. w13x R. Geick, C.H. Perry, Phys. Rev. 146 (1966) 543. w14x H.K. Pulker, Proceedings of the Eighth Inter. Conf. on Vac. Metallurgy, Linz, 1985, 115.
w15x K. Hamrin, G. Johansson, U. Gelious, C. Nordling, K. Siegbahn, Phys. Scr. 1 (1970) 277. w16x C.D. Wagner, W.M. Riggs, L.E. Davis, J.F. Moulder, G.E. Muilenberg, Handbook of X-ray Photoelectron Spectroscopy, Perkin Elmer, Physical Electronics Division, Eden Prairie, MN, 1979. w17x H. Kunzli, ¨ P. Gantenbein, R. Steiner, P. Oelhafen, Fresenius J. Anal. Chem. 346 (1993) 41.