a-C:H/a-C:H(N) thin film deposition using 2.45 GHz expanding surface wave sustained plasmas

Abstract

Thin film properties such as homogeneity (radial profiles), optical constants, carbon density in the film, and the surface structures are strongly dependent on deposition conditions. We have investigated a-C:H/a-C:H(N) thin film deposition by expanding Ar-CH 4 and Ar/N 2 -CH 4 surface wave sustained plasmas at a frequency of 2.45 GHz. The influence of the plasma parameters such as pressure, input power, gas mixture rate, and an external bias voltage on the change of the film properties is systematically studied. An external bias applied to the substrate leads to more dense and harder a-C:H films, i.e. change from soft polymer-like to hard diamond-like. Rutherford backscattering and atomic force microscope surface topology confirm the densification of the films.

On the Mechanism of Nitrogenated Carbon Film Deposition by PACVD in the Presence of Nitrogen. A Cryo‐Trapping Assisted Mass Spectrometric Study

“…A simple scheme to reconcile the chemical sputtering observations with the results from the scavenger mixture would imply the recombination of the plasma-born radicals and the surface species created by nitrogenated species. Whether energetic ions, or simply free N atoms, are required for such surface modification is still unknown, [31] but a very low energy threshold seems to exist, according to recent results. [32] In the absence of carbon radical impact at the surface, only formation of CN-containing simple molecules will be produced, while recombination of the surface-produced and plasma-produced radicals will preferentially happen if methane is present in the gas mixture.…”

Capacitively coupled radio-frequency discharges in nitrogen at low pressures

“…Although nitrogen plasmas have been studied for many years, and despite their growing interest in applications, there is only partial knowledge about their behaviour under ccrf discharge conditions. In fact, the majority of papers on N 2 plasmas concern dc [44][45][46][47][48][49][50], high-frequency (microwave) discharges [51][52][53][54][55][56] and inductively coupled discharges [57], and focus essentially on their kinetic description. Usually, these are zero-dimensional self-consistent models, coupling the two-term electron Boltzmann equation (or just assuming a Maxwellian electron distribution function) to the rate balance equations of different vibrationally and electronically excited (molecular and atomic) states, yielding the electron energy distribution function (eedf), the vibrational distribution function (vdf) of the ground-state nitrogen molecules and the populations of the excited species considered.…”

Growth and Microstructure of Nanoscale Amorphous Carbon Nitride Films Deposited by Electron Beam Irradiation of 1,2-Diaminopropane

“…The deposition of amorphous carbon nitride thin films is typically accomplished in low pressure, plasma environments. − Under these conditions, growth is a consequence of complex surface reactions involving an array of reactive species, including ions, radicals, photons, and electrons, the later including secondary electrons produced by the interaction of incident photons and electrons with the substrate . To date, uncovering the specific role that individual species, such as electrons, play in controlling the deposition rate as well as the microstructure of amorphous carbon nitride thin films has been hampered by the complexity of the gas phase medium. − Thus, although the properties of carbon nitride films are known to be strongly dependent upon macroscopic deposition parameters (input power, gas phase composition), − only a few of the specific surface processes involved in film growth have been identified…”

“…19 To date, uncovering the specific role that individual species, such as electrons, play in controlling the deposition rate as well as the microstructure of amorphous carbon nitride thin films has been hampered by the complexity of the gas phase medium. [20][21][22] Thus, although the properties of carbon nitride films are known to be strongly dependent upon macroscopic deposition parameters (input power, gas phase composition), [23][24][25][26] only a few of the specific surface processes involved in film growth have been identified. 27 The irradiation of solid substrates in the presence of background hydrocarbons by electrons has been identified as the reason for the unwanted formation of amorphous carbonaceous films on windows and lenses in electron microscopes.…”