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Atomic force microscope (AFM), lateral force microscope and AFM-based scratch and wear testing techniques were used to evaluate and compare the surface roughness, tribological and mechanical properties of thin (2.7–43 nm) tetrahedral amorphous carbon coatings prepared by pulsed cathodic arc discharge. It was found that surface roughness of ultrathin (2–8 nm) coatings was mainly determined by the roughness of the Si substrate and their average density strongly depended on their thickness. Poor friction, mechanical properties of thinner (2.7–15 nm) coatings can be associated with their low average density. The dense coatings (>15 nm) had lower friction coefficient, better scratch and wear resistance properties that were independent of their thickness. It appears that the over 15-nm coatings studied are feasible for some wear-resistant and tribological applications.

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

D. Liu, Günther Benstetter, Y. Liu, X. Xang, S. Yu, T. Ma

Medium- to high-pressure plasma deposition of a-C:H films by dielectric barrier discharge

New Diamond and Frontier Carbon Technology, vol. 13, no. 4, pp. 191-206

2003

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

D. Li, Günther Benstetter, Edgar Lodermeier, I. Akula, I. Dudarchyk, Y. Liu, T. Ma

SPM investigation of diamond-like carbon and carbon nitride films

Surface & Coatings Technology, vol. 172, no. 2-3, pp. 194-203

2003

DOI: 10.1016/S0257-8972(03)00338-4

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Scanning probe microscopy was used to evaluate and compare the surface roughness, mechanical and tribological properties of hydrogenated (a-C:H) and tetrahedral (ta-C) diamond-like carbon (DLC) and amorphous carbon nitride (a-C:N) films. Compared to the a-C:H and a-C:N films, the ta-C films exhibit the lowest surface roughness. The soft surface layers of DLC and a-C:N films were revealed by nanowear tests and their thickness varies over the range of 0.2 to 4.1 nm. The nanoscale friction coefficient measurements from lateral force microscopy shows that these films have obviously different friction coefficients. The lower friction coefficients of ta-C and a-C:N films can be attributed to the existence of soft graphite-like surface structure. We proposed the deposition processes of DLC and a-C:N films, where their surface roughness, structure and mechanical properties were associated with the vapor plasma particle energy distribution.

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

D. Liu, Günther Benstetter, Y. Liu, T. Ma

Surface roughness, scratch resistance and tribological properties of hydrogenated amorphous carbon coatings prepared by low-pressure dielectric barrier discharge

Surface & Coatings Technology, vol. 174-175, no. September/Oktober, pp. 310-315

2003

DOI: 10.1016/S0257-8972(03)00649-2

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In this study, we explored the surface roughness, scratch resistance and tribological properties of hydrogenated amorphous carbon (a-C:H) coatings deposited on silicon substrates from low-pressure dielectric barrier discharge (DBD) plasmas of CH4 by using an atomic force microscope (AFM), AFM-based scratch testing technique and lateral force microscope. The AFM and scratch measurements show that the surface roughness and scratch resistance of these a-C:H coatings strongly depend on the Pd value (the product of CH4 pressure P, and discharge gas spacing d) and the a-C:H coatings deposited at suitable Pd value (typically 350 Pa mm) exhibit lower surface roughness and better scratch resistance. The a-C:H coatings deposited at the Pd value of 350–1750 Pa mm have the typical friction coefficient of approximately 0.13. The lower friction coefficient (0.11) of the a-C:H coating deposited at the smaller Pd value of 245 Pa mm can be associated with its graphite-like surface structure. The results indicate the coating structure changes from the one of graphite-like to diamond-like to polymer-like with the Pd value increasing from 245 to 1750 Pa mm. The relationship between the measured coating properties and the DBD deposition processes was presented.

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

D. Liu, Günther Benstetter, Edgar Lodermeier, X. Chen, J. Ding, Y. Liu, J. Zhang, T. Ma

Surface and structural properties of ultrathin diamond-like carbon coatings

Diamond and Related Materials, vol. 12, pp. 1594-1600

2003

DOI: 10.1016/S0925-9635(03)00248-6

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Nanoscale wear resistance, friction, and electrical conduction tests using atomic force microscope (AFM) have been conducted on ultrathin diamond-like carbon (DLC) coatings, including tetrahedral amorphous carbon (ta-C) deposited using pulsed cathodic arc (PCA) and filtered-PCA, and hydrogenated amorphous carbon (a-C:H) deposited using electron cyclotron resonance—chemical vapor deposition (ECR-CVD). The low-resistant layers at the surfaces of these thin DLC coatings were revealed by AFM-based nanowear tests. Their thickness is mainly determined by the deposition methods and does not show an obvious variation with the coating thickness decreasing from tens of nm to a few nm. The ∼3 nm ta-C coatings from PCA and filtered-PCA deposition were found to have the stable bulk structure beneath the thin (0.3–0.95 nm) surface layers. The ∼3 nm a-C:H coating from ECR-CVD had the extremely low load-carrying capacity and exhibited the evidence of coating delamination, which can be related to the thicker (1.5±0.1 nm) soft surface layers of a-C:H coatings. The results from conducting-AFM measurements indicate that a-C:H coatings have H and sp3 C enrichment surface layers while the soft surface layers of ta-C coatings have graphite-like structure. The nanoscale friction coefficients of these thin ta-C and a-C:H coatings were compared by AFM-based lateral force microscope. The lower friction coefficient of ta-C coatings can be attributed to the existence of graphite-like surface structure.

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

M. Ruprecht, Günther Benstetter, D. Hunt

A review of ULSI failure analysis techniques for DRAMs , Part II: defect isolation and visualization

Introductory Invited Paper

Microelectronics Reliability, vol. 43, pp. 17-41

2003

DOI: 10.1016/S0026-2714(02)00295-0

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In this paper the basic techniques for defect isolation and visualization used in physical failure analysis of trench technique dynamic random access memories (DRAMs) are reviewed. The methods described are state-of-the-art for DRAM failure analysis down to 0.14 μm feature size and beyond. In addition to defect isolation and defect visualization from the front side of a die, the backside preparation approach is reviewed. Beginning with basic sample preparation techniques including mechanical polishing, wet and dry etching and focused ion beam (FIB) applications advantages and disadvantages of various techniques are discussed. In the second section of the paper different types of optical microscopes are covered as well as scanning and transmission electron microscopes. The imaging capabilities of the FIB systems are included in this section. Finally, some applications of scanning probe techniques especially for dopant measurements and thin oxide characterization are described.

Elektrotechnik und Medientechnik IQMA Maschinenbau und Mechatronik

Zeitschriftenartikel

D. Liu, Günther Benstetter, Werner Frammelsberger

The effect of the surface layer of tetrahedral amorphous carbon films on their tribological and electron emission properties investigated by atomic force microscopy

Applied Physics Letters, vol. 82, pp. 3898-3900

2003

DOI: 10.1063/1.1581367

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The nanowear resistance, tribological, and field emissionproperties of tetrahedral amorphous carbon (ta-C) films have been analyzed by atomic force microscope (AFM)-based wear testing technique, lateral force microscope, and conducting AFM. The ta-C films grown by filtered pulsed cathodic arc discharge were found to have soft surface layers, thick, which contribute to an improvement of their field emissionproperties. The low friction coefficient between the nanotip and film surface is correlated to one or two graphite-like atomic layers at the ta-C film surfaces. The analysis of Fowler–Nordheim tunneling currents indicates the formation of filament-like emission channels in amorphous carbon films.

Elektrotechnik und Medientechnik IQMA

Zeitschriftenartikel

D. Liu, Günther Benstetter, Edgar Lodermeier, J. Vancea

Influence of the incident angle of energetic carbon ions on the properties of tetrahedral amorphous carbon (ta-C) films

Journal of Vacuum Science & Technology A, vol. 21, pp. 1655-1670

2003

DOI: 10.1116/1.1597888

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Tetrahedral amorphouscarbon (ta-C) films have been grown on Ar+-beam-cleaned silicon substrates by changing the incident angle of energetic carbon ions produced in the plasma of pulsed cathodic vacuum arc discharge. Their surface roughness, deposition rate, composition, and mechanical and frictional properties as a function of the incident angle of energetic carbon ions were reported. The substrate holder can be rotated, and so an angle of deposition was defined as the angle of ion flux with respect to the substrate surface. While the deposition angle is varied from 20° to 59°, the root-mean-square (rms) roughness decreases from 0.5 to 0.1 nm, then it turns to increase at a slow rate when the deposition angle is over 77°. The variation correlates well with the one of hardness with the deposition angle and the films with lower rms roughness exhibit the higher hardness. The soft graphite-like surface layers existing at the surfaces of these films were revealed by atomic force microscopy-based nanowear tests and their thickness increases from 0.35 to 2.9 nm with the deposition angle decreasing from 90° to 30°. The soft surface layer thickness can have a great effect on the sp3 contents measured by x-ray photoelectron spectra. Nanoscale friction coefficient measurements were performed from lateral force microscopy by using a V-shaped Si3N4 cantilever. The low friction coefficients (0.076–0.093) of ta-C films can be attributed to their graphite-like surface structure. The implications of these results on the mechanisms proposed for the film formation were discussed.

Elektrotechnik und Medientechnik IQMA Maschinenbau und Mechatronik

Vortrag

Werner Frammelsberger, Günther Benstetter, T. Schweinböck, R. Stamp, J. Kiely

Advanced Analysis of Thin and Ultrathin SiO2/Si Interfaces with Combined Atomic Force Microscopy Methods

29th International Symposium for Testing and Failure Analysis, Santa Clara, CA, USA, pp. 406-412

2003

Elektrotechnik und Medientechnik IQMA

Vortrag

Günther Benstetter, R. Schmidt, S. Ascher, M. Kerber, Johannes Grabmeier, A. Huber

Evaluation of thin oxide reliability by means of wafer level stress-testing

8th European Parametric Test User Group Meeting, Prien am Chiemsee

2002