Ultra-thin tetrahedral amorphous carbon films with strong adhesion, as measured by nanoscratch testing

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Abstract

Amorphous carbon can form hard and dense films, which find applications for tooling components, magnetic recording, etc. The challenge is to prepare hard layers that have good adhesion to the substrate. Moreover, mechanical characterisation of sub-20 nm layer is still difficult and semi-quantitative. The paper is addressing these issues. We prepared 10-nm and 50-nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H) films, respectively, by filtered cathodic arc deposition (FCVA) and plasma enhanced chemical vapour deposition (PECVD). The films were characterised by nanoindentation and nano-scratching. With such hard films, blunting of the diamond tip can affect the measurements and we used a hardness slope ratio protocol, which gave more accurate results. The ta-C films were the hardest and more wear resistant, i.e. for the 50-nm thick ta-C film on Al2O3-TiC; H (25 nm) = 51 GPa and residual depth = 4 nm for a 5 mN scratch load. This is typical of the FCVA conditions, i.e. a relatively high energy,mono-energetic (approx. 25 eV) non-hydrogenated ion flux, resulting in formation of a dense sp(3) network. Ramping the scratch load to observe delamination events, we measured the highest critical loads (approx. 6 mN) again for the ta-C films. We used SEM/EDX thickness measurements to confirm these delaminations. Again, the ta-C films show the best adhesion. We believe that, the FCVA beam is sufficiently energetic toprovide a dense and rigid network structure and a good ion beam mixing in the substrate but, appropriately, not enough to produce the large internal stress observed at - 100 V substrate bias. (C) 2003 Elsevier B.V. All rights reserved.
LanguageEnglish
Pages1385-1390
JournalDiamond and Related Materials
Volume13
Issue number4-8
DOIs
Publication statusPublished - Apr 2004

Fingerprint

Carbon films
Amorphous carbon
Amorphous films
Adhesion
Testing
Delamination
Substrates
Diamond
Thickness measurement
Magnetic recording
Nanoindentation
Plasma enhanced chemical vapor deposition
Ion beams
Energy dispersive spectroscopy
Residual stresses
Diamonds
Hardness
Wear of materials
Ions
Fluxes

Keywords

  • hardness
  • internal stress
  • critical load
  • adhesion

Cite this

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title = "Ultra-thin tetrahedral amorphous carbon films with strong adhesion, as measured by nanoscratch testing",
abstract = "Amorphous carbon can form hard and dense films, which find applications for tooling components, magnetic recording, etc. The challenge is to prepare hard layers that have good adhesion to the substrate. Moreover, mechanical characterisation of sub-20 nm layer is still difficult and semi-quantitative. The paper is addressing these issues. We prepared 10-nm and 50-nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H) films, respectively, by filtered cathodic arc deposition (FCVA) and plasma enhanced chemical vapour deposition (PECVD). The films were characterised by nanoindentation and nano-scratching. With such hard films, blunting of the diamond tip can affect the measurements and we used a hardness slope ratio protocol, which gave more accurate results. The ta-C films were the hardest and more wear resistant, i.e. for the 50-nm thick ta-C film on Al2O3-TiC; H (25 nm) = 51 GPa and residual depth = 4 nm for a 5 mN scratch load. This is typical of the FCVA conditions, i.e. a relatively high energy,mono-energetic (approx. 25 eV) non-hydrogenated ion flux, resulting in formation of a dense sp(3) network. Ramping the scratch load to observe delamination events, we measured the highest critical loads (approx. 6 mN) again for the ta-C films. We used SEM/EDX thickness measurements to confirm these delaminations. Again, the ta-C films show the best adhesion. We believe that, the FCVA beam is sufficiently energetic toprovide a dense and rigid network structure and a good ion beam mixing in the substrate but, appropriately, not enough to produce the large internal stress observed at - 100 V substrate bias. (C) 2003 Elsevier B.V. All rights reserved.",
keywords = "hardness, internal stress, critical load, adhesion",
author = "JP Quinn and P Lemoine and PD Maguire and JAD McLaughlin",
note = "14th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide, Salzburg, AUSTRIA, SEP 08-12, 2003",
year = "2004",
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T1 - Ultra-thin tetrahedral amorphous carbon films with strong adhesion, as measured by nanoscratch testing

AU - Quinn, JP

AU - Lemoine, P

AU - Maguire, PD

AU - McLaughlin, JAD

N1 - 14th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide, Salzburg, AUSTRIA, SEP 08-12, 2003

PY - 2004/4

Y1 - 2004/4

N2 - Amorphous carbon can form hard and dense films, which find applications for tooling components, magnetic recording, etc. The challenge is to prepare hard layers that have good adhesion to the substrate. Moreover, mechanical characterisation of sub-20 nm layer is still difficult and semi-quantitative. The paper is addressing these issues. We prepared 10-nm and 50-nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H) films, respectively, by filtered cathodic arc deposition (FCVA) and plasma enhanced chemical vapour deposition (PECVD). The films were characterised by nanoindentation and nano-scratching. With such hard films, blunting of the diamond tip can affect the measurements and we used a hardness slope ratio protocol, which gave more accurate results. The ta-C films were the hardest and more wear resistant, i.e. for the 50-nm thick ta-C film on Al2O3-TiC; H (25 nm) = 51 GPa and residual depth = 4 nm for a 5 mN scratch load. This is typical of the FCVA conditions, i.e. a relatively high energy,mono-energetic (approx. 25 eV) non-hydrogenated ion flux, resulting in formation of a dense sp(3) network. Ramping the scratch load to observe delamination events, we measured the highest critical loads (approx. 6 mN) again for the ta-C films. We used SEM/EDX thickness measurements to confirm these delaminations. Again, the ta-C films show the best adhesion. We believe that, the FCVA beam is sufficiently energetic toprovide a dense and rigid network structure and a good ion beam mixing in the substrate but, appropriately, not enough to produce the large internal stress observed at - 100 V substrate bias. (C) 2003 Elsevier B.V. All rights reserved.

AB - Amorphous carbon can form hard and dense films, which find applications for tooling components, magnetic recording, etc. The challenge is to prepare hard layers that have good adhesion to the substrate. Moreover, mechanical characterisation of sub-20 nm layer is still difficult and semi-quantitative. The paper is addressing these issues. We prepared 10-nm and 50-nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H) films, respectively, by filtered cathodic arc deposition (FCVA) and plasma enhanced chemical vapour deposition (PECVD). The films were characterised by nanoindentation and nano-scratching. With such hard films, blunting of the diamond tip can affect the measurements and we used a hardness slope ratio protocol, which gave more accurate results. The ta-C films were the hardest and more wear resistant, i.e. for the 50-nm thick ta-C film on Al2O3-TiC; H (25 nm) = 51 GPa and residual depth = 4 nm for a 5 mN scratch load. This is typical of the FCVA conditions, i.e. a relatively high energy,mono-energetic (approx. 25 eV) non-hydrogenated ion flux, resulting in formation of a dense sp(3) network. Ramping the scratch load to observe delamination events, we measured the highest critical loads (approx. 6 mN) again for the ta-C films. We used SEM/EDX thickness measurements to confirm these delaminations. Again, the ta-C films show the best adhesion. We believe that, the FCVA beam is sufficiently energetic toprovide a dense and rigid network structure and a good ion beam mixing in the substrate but, appropriately, not enough to produce the large internal stress observed at - 100 V substrate bias. (C) 2003 Elsevier B.V. All rights reserved.

KW - hardness

KW - internal stress

KW - critical load

KW - adhesion

U2 - 10.1016/j.diamond.2003.11.025

DO - 10.1016/j.diamond.2003.11.025

M3 - Article

VL - 13

SP - 1385

EP - 1390

JO - Diamond and Related Materials

T2 - Diamond and Related Materials

JF - Diamond and Related Materials

SN - 0925-9635

IS - 4-8

ER -