Plasma beam deposited amorphous hydrogenated carbon: Improved film quality at higher growth rate

et al. 1996

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Amorphous hydrogenated carbon films have been deposited on crystalline silicon and on glass from an expanding thermal plasma. Two deposition parameters have been varied: the electric current through the plasma source and the admixed acetylene flow. No energetic ion bombardment has been applied during deposition. Ex situ analysis of the films yields the infrared refractive index, hardness, Young's modulus, optical band gap, bonded hydrogen content, and the total hydrogen and mass density. The infrared refractive index describes the film properties independent of which plasma deposition parameter ͑arc current or acetylene flow͒ has been varied. The hardness, Young's modulus, sp 2 /sp 3 ratio, and mass density increase with increasing refractive index. The optical band gap and hydrogen content of the films decrease with increasing refractive index. It is demonstrated that plasma-beam-deposited diamondlike a-C:H has similar properties as material deposited with conventional plasma-enhanced chemical-vapor-depositions techniques under energetic ion bombardment.

Section: Resultsmentioning

confidence: 99%

Optical and mechanical properties of plasma-beam-deposited amorphous hydrogenated carbon

Gielen

Kleuskens

et al. 1996

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Section: Introductionmentioning

confidence: 99%

“…14,15 Using an expanding thermal plasma deposition rates up to 75 nm/s have been obtained without loss of material quality. The material properties even improve at increasing growth rate 14,16 and the films exhibit diamondlike quality. 15 Variation of the plasma settings and the subsequent change in material properties is obtained by varying the ionization degree of the expanding plasma and the admixed acetylene precursor flow.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the best material quality is obtained when the residual ion density in front of the growing film is minimal. 14,17 Next to the effect of a substrate bias, another substrate property is considered to be important during the deposition of a-C:H: the substrate temperature. In previous deposition experiments the substrate holder was water-cooled without applying an active temperature control.…”

Section: Introductionmentioning

confidence: 99%

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Effect of substrate conditions on the plasma beam deposition of amorphous hydrogenated carbon

Gielen

Kessels

et al. 1997

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A study on the effect of substrate conditions was performed for the plasma beam deposition of amorphous hydrogenated carbon ( a-C:H) from an expanding thermal argon/acetylene plasma on glass and crystalline silicon. A new substrate holder was designed, which allows the control of the substrate temperature independent of the plasma settings with an accuracy of 2 K. This is obtained via a combination of a good control of the holder’s yoke temperature and the injection of helium gas between thermally ill connected parts of the substrate holder system. It is demonstrated that the substrate temperature influences both the a-C:H material quality and the deposition rate. The deposition rate and substrate temperature are presented as the two parameters which determine the material quality. In situ studies prove that the deposition process is constant in time and that thermally activated etching processes are unlikely to contribute significantly during deposition. Preliminary experiments with an additional substrate bias reveal that an energetic ion bombardment of the growing film surface does not influence the deposition process. A tentative deposition model is proposed based on the creation and destruction of active sites, which depend on the particle fluxes towards the substrate and the substrate temperature. This model allows the qualitative explanation of the observed deposition results.

“…A similar setup was used in the past to deposit hydrogenated amorphous carbon at high rates. 27 Background gas is sampled from the plasma by a Balzers QMS 200 Prisma residual gas analyzer ͑RGA͒ through an orifice of 100 m. The RGA is pumped by a turbopump (60 l /s), positioned directly under the quadrupole. The operating pressure during measurements is in the 10 Ϫ6 mbar range, depending on the chamber pressure.…”

Section: Methodsmentioning

confidence: 99%

Plasma chemistry aspects of a-Si:H deposition using an expanding thermal plasma

Severens

Kessels

et al. 1998

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118

The plasma chemistry of an argon/hydrogen expanding thermal arc plasma in interaction with silane injected downstream is analyzed using mass spectrometry. The dissociation mechanism and the consumption of silane are related to the ion and atomic hydrogen fluence emanating from the arc source. It is argued that as a function of hydrogen admixture in the arc, which has a profound decreasing effect on the ion-electron fluence emanating from the arc source, the dissociation mechanism of silane shifts from ion-electron induced dissociation towards atomic hydrogen induced dissociation. The latter case, the hydrogen abstraction of silane, leads to a dominance of the silyl (SiH 3 ) radical whereas the ion-electron induced dissociation mechanism leads to SiH x (xϽ3) radicals. In the pure argon case, the consumption of silane is high and approximately two silane molecules are consumed per argon ion-electron pair. It is shown that this is caused by consecutive reactions of radicals SiH x (xϽ3) with silane. Almost independent of the plasma conditions used, approximately one H 2 is produced per consumed SiH 4 molecule. Disilane production is observed which roughly scales with the remaining silane density. Possible production mechanisms for both observations are discussed.