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

Abstract

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.

Optical and chemical characterization of expanding thermal plasma-deposited carbon-containing silicon dioxide-like films

“…The substrate is placed at a distance of 60 cm from the nozzle and its temperature (T sub ) is kept constant at 50°C using ohmic heating and liquid N 2 /watercooling systems. A good thermal contact between the substrate holder and the samples is assured by a small He back flow (Φ He = 1.5 sccs): this leads to a very limited substrate temperature increase due to plasma ignition, approximately 10°C, as determined from infrared interferometric measurements [26]. …”

Hard graphitelike hydrogenated amorphous carbon grown at high rates by a remote plasma

“…A comparative study shows C 2 H 2 as a better candidate over CH 4 and C 6 H 6 , which reveals that chemistry plays an important role during deposition even under such conditions. 4,[17][18][19][20] Studies dedicated to reaction mechanism involved in such plasmas have been taken up by our group at several occasions. 1 Depositing a-C:H films at high growth rates without compromising the material quality has been a scientific and technological challenge, where the expanding thermal plasma chemical vapor deposition ͑ETP-CVD͒ has emerged as a promising technique.…”

“…11 For industrial applications, these ion or physical based deposition techniques have the downside of slow growth rates, typically up to a few nm/s. 4,[17][18][19][20][21][22][23][24][25][26][27] Ionization of acetylene molecules via electron impact is not possible due to the low electron temperature. 12 In the ETP-CVD moderately hard films have been achieved at high growth rates above 10 nm/s entirely by tuning the plasma chemistry.…”

B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon

“…1,2 Remote plasma deposition is used to deposit, among others, diamondlike carbon films with a nanohardness in excess of 13 GPa at high deposition rates ͑Ͼ10 nm/ s͒, while maintaining good adhesion and chemical stability ͑see, e.g., Refs. 1, 3, and 4, and references therein͒.…”