Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices

Krauss, A. R.; Auciello, Orlando; Gruen, D. M.; Jayatissa, Ahalapitiya H.; Sumant, Anirudha V.; Tuček, J.; Mancini, Derrick C.; Moldovan, N.; Erdemir, Ali; Ersoy, Daniel; Gardos, Michael N.; Busmann, H.‐G.; Meyer, Eva-Maria; Ding, Mingqing

doi:10.1016/s0925-9635(01)00385-5

Cited by 356 publications

(151 citation statements)

References 37 publications

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“…Polycrystalline diamond films, among which ultrananocrystalline and nanocrystalline diamond (UNCD and NCD, respectively), produced by plasma deposition, have very promising tribological, biological and electrical applications [49][50][51]. NCD films are typically grown under conventional diamond PE-CVD conditions, i.e., a CH 4 /H 2 mixture at a ratio 1/99, and a substrate temperature above 1000 K [52], resulting in columnar diamond crystals with diameters below 500 nm [51].…”

Section: Modeling the Plasma Chemistry For The Growth Of Nanostructurmentioning

confidence: 99%

Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

Bogaerts¹,

Eckert²,

Mao³

et al. 2011

J. Phys. D: Appl. Phys.

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In this review paper, an overview is given of different modeling efforts for plasmas used for the formation and growth of nanostructured materials. This includes both the plasma chemistry, providing information on the precursors for nanostructure formation, as well as the growth processes itself. We limit ourselves to carbon (and silicon) nanostructures. Examples of the plasma modeling comprise nanoparticle formation in silane and hydrocarbon plasmas, as well as the plasma chemistry giving rise to carbon nanostructure formation, such as (ultra)nanocrystalline diamond ((U)NCD) and carbon nanotubes (CNTs). The second part of the paper deals with the simulation of the (plasma-based) growth mechanisms of the same carbon nanostructures, i.e., (U)NCD and CNTs, both by mechanistic modeling and detailed atomistic simulations. IntroductionLow temperature plasmas are playing an increasingly important role for the formation and growth of nanostructures and nanostructured materials (e.g., [1][2][3][4][5][6][7]). To improve the performance of these plasma growth processes, a good insight is desired in the plasma and in the interaction with the growing nanostructures. This insight can be obtained by experimental research, but the latter is not always straightforward, in view of the small dimensions of the nanomaterials and the possible disturbance of the plasma characteristics, e.g., when introducing a probe. Therefore, computer simulations can be very useful to assist in the experimental developments.In the present paper, we will give an overview of different modeling efforts that have been presented in the literature for plasmas used for nanostructure formation. This includes two different aspects. First, a thorough understanding of the plasma behavior is needed. This comprises background gas flow and heating (i.e., fluid dynamics), gas breakdown, transport and heating of the electrons and the so-called heavy particles, as well as the plasma chemistry, i.e., creation and destruction of the various plasma species by chemical reactions. Modeling of the plasma chemistry can give indications on which species are important precursors for the growth of nanostructured materials and how the plasma operating conditions can be tuned to optimize the growth process. Therefore, in this paper we will mainly focus on the plasma chemistry modeling. Several plasma modeling approaches exist in literature, such as analytical models, zero-dimensional (0D) chemical kinetics simulations, fluid models (describing the chemical kinetics as well as fluid dynamics), solving the Boltzmann transport equation, Monte Carlo (MC) and particle-in-cell (PIC)-MC simulations, as well as hybrid methods, combining the above (e.g., MC + fluid) models. For describing the plasma chemistry, the 0D chemical kinetics approach is often applied, as it can take into account a large number of different species and reactions without too much computational effort. However, it assumes a spatially uniform plasma composition and does not consider transport of the plasm...

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Section: Modeling the Plasma Chemistry For The Growth Of Nanostructurmentioning

confidence: 99%

Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

Bogaerts¹,

Eckert²,

Mao³

et al. 2011

J. Phys. D: Appl. Phys.

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“…These films exhibited a residual compressive stress of 370Ϯ 1 MPa measured using a Tencor Flexus 2320A stress measurement tool. NEXAFS spectroscopy was used to determine the chemical bonding nature of the films, especially for the presence of sp 3 and sp 2 content in the near-surface region ͑topϳ 4 nm͒ of the films. 28 A NEXAFS spectrum taken on the topside of a hydrogen-terminated UNCD film grown with the conditions indicated above is shown in Fig.…”

Section: Film Growth and Characterizationmentioning

confidence: 99%

“…Based on NEXAFS measurements on HFCVD grown UNCD films and the corresponding reference spectra obtained on single-crystal diamond and highly oriented pyrolytic graphite ͑HOPG͒, we estimate the sp 2 content of the films to be 5.8% using the normalization method described by Lenardi et al 28 The sp 2 content observed in the HFCVD UNCD films studied here is similar to the 2 -5 % sp 2 content observed in MPCVD films grown at 800°C. 3 Most of this sp 2 -bonded carbon is present at the grain boundaries; some fraction may be due to adsorbates and surface reconstruction. Hydrogen termination 29 of the surface using a hot filament process resulted in the reduction in sp 2 content in the near-surface region to 4.3%.…”

Section: Film Growth and Characterizationmentioning

confidence: 99%

“…Diamond, the stiffest material known, can be grown as a conformal thin film on a variety of surfaces in a form known as ultrananocrystalline diamond ͑UNCD͒ ͑grain size ϳ2-5 nm͒. [1][2][3] UNCD films were originally grown using microwave plasma chemical vapor deposition ͑MPCVD͒, and Young's modulus 4,5 and hardness 5 of films grown using this well-established recipe have been measured. These films exhibit smooth surfaces 1 and mechanical properties close to single-crystal diamond despite the high volume fraction of grain boundaries and the presence of atoms such as hydrogen.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical stiffness and dissipation in ultrananocrystalline diamond microresonators

et al. 2009

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We have characterized mechanical properties of ultrananocrystalline diamond UNCD thin films grown using the hot filament chemical vapor deposition HFCVD technique at 680 °C, significantly lower than the conventional growth temperature of 800 °C. The films have 4.3% sp2 content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, 1 m thick, exhibit a net residual compressive stress of 3701 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 8382 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum UHV conditions in a customized UHV atomic force microscope system to determine Young's modulus as well as mechanical dissipation of cantilever structures at room temperature. Young's modulus is found to be 79030 GPa. Based on these measurements, Poisson's ratio is estimated to be 0.0570.038. The quality factors Q of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD resonators. We have characterized mechanical properties of ultrananocrystalline diamond ͑UNCD͒ thin films grown using the hot filament chemical vapor deposition ͑HFCVD͒ technique at 680°C, significantly lower than the conventional growth temperature of ϳ800°C. The films have ϳ4.3% sp 2 content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, ϳ1 m thick, exhibit a net residual compressive stress of 370Ϯ 1 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 838Ϯ 2 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum ͑UHV͒ conditions in a customized UHV atomic force microscope system to determine Young's modulus as well as mechanical dissipation of cantilever structures at room temperature. Young's modulus is found to be 790Ϯ 30 GPa. Based on these measurements, Poisson's ratio is estimated to be 0.057Ϯ 0.038. The quality factors ͑Q͒ of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD re...

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“…9,10 Nevertheless, the friction and wear of nanocrystalline diamond are quite anisotropic and depends on various factors, such as the chemical reactivity of the surface, crystallite size, crystallographic orientation, existence of dangling covalent bonds, sliding direction of oriented planes, surface roughness, properties of transfer layers, test environment and finally test parameters which influence the wear behavior, such as load and sliding velocity. 8,[11][12][13][14][15] In addition to all known important factors and tribological test parameters which may influence the wear behavior of the NCD films, the amount of hydrogen and sp 3 /sp 2 bonding ratio play a dominant role in the friction and wear performances of these materials. 16 There are several physical and chemical methods to synthesize NCD films.…”

Section: Introductionmentioning

confidence: 99%

Tribological properties of nanocrystalline diamond films deposited by hot filament chemical vapor deposition

et al. 2012

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The dependence of the structural and morphological properties of nanocrystalline diamond films grown by hot filament chemical vapor deposition on the substrate temperature was studied. Friction coefficients of these films were measured and found to vary from high to ultra low, depending on the chemical nature of the films i.e., sp2 and sp3 phase fractions. For all films, the friction coefficient was found to decrease with increase in sp2/sp3 phase fraction. The wear rate follows the trend of the friction coefficient and was likewise found to depend on the structural and morphological properties of the films. For all the films, the friction coefficient is found to decrease with normal load which is ascribed to sliding induced surface amorphization/graphitization

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Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices

Cited by 356 publications

References 37 publications

Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

Mechanical stiffness and dissipation in ultrananocrystalline diamond microresonators

Tribological properties of nanocrystalline diamond films deposited by hot filament chemical vapor deposition

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