The effect of excitation frequency on emission spectra of polymerization plasmas

Abstract

The excitation frequency is known to have an effect on the rate of deposition of polymer thin films produced by a glow discharge process. This has been attributed to changes in the electron energy distribution function (EEDF). Any appreciable change in the EEDF would be expected to be revealed by plasma emission spectroscopy. Our findings are herein reported for deposition plasmas containing C3 H6 and Ar at dc, 40-kHz, and 27.12-MHz excitation frequencies; included are data on film deposition rate and optical clarity which also vary with excitation frequency.

Influence of the excitation frequency on CH4/H/H2plasmas for diamond film deposition: electron energy distribution function and atomic hydrogen concentration

“…However, even working at constant power density (option (b)), there is also experimental evidence showing that θ decreases with increasing pressure (at constant excitation frequency) [42], i.e. the electron density increases (since P A is kept constant) with increasing pressure and that, on the other side, the electron density grows (at constant pressure), with increasing excitation frequency [43,44]. Therefore, these facts need to be taken into consideration when studying how the EEDF changes, at constant power density, with excitation frequency and pressure.…”

“…Therefore, these facts need to be taken into consideration when studying how the EEDF changes, at constant power density, with excitation frequency and pressure. Consequently, we have assumed in our model that the ionization degree (η i ) grows, at constant pressure and power density, with increasing excitation frequency [43,44]. The ionization degrees considered for each frequency are shown in table 1 and the corresponding average electron densities associated with each frequency, at constant pressure, are derived from the definition of the ionization degree, η i = n e /N T , N T being the total particle density (note that the electron density is thus a parameter of our model).…”

Characterization of diamond-like carbon (DLC) thin films prepared by r.f. magnetron sputtering

“…Different techniques are used for the preparation of these DLC films: ionic implantation, sputtering or plasma assisted chemical vapor deposition techniques (CVD). All these techniques have in common the use of different mixtures of hydrocarbons for the growth of carbon amorphous hydrogenate (a-C:H), films due to the role that hydrogen plays in the stabilization of the sp 3 bonds of the diamond, on the surface of the film that are producing [1]. In the type sputtering discharges, the plasma of the discharge is used to generate the activation of such chemical precursors as the neutral radicals and the ions taken place by the decomposition of the hydrocarbons by electronic impact.…”

“…(13.56 MHz) is monitored in situ by means of optical emission spectroscopy (OES) technique, used to grow diamond-like type thin films, using different Ar/CH 4 ratios in the mixture. The relationship between the intensities of the lines H α /H β of the hydrogen represents a measure of the relative change in the electronic temperature of the plasma [3]. They are correlated with the quotient (I D /I G ) between the intensities of the diamond and graphite peaks obtained from Raman spectroscopy analyses and with bonding structure of the a:C-H bonds in the films, determinated by Infrared spectroscopy (IRS).…”