Radio frequency or microwave plasma reactors? Factors determining the optimum frequency of operation

Abstract

It is now generally accepted that the frequency ω/2π at which a high frequency (hf) discharge is sustained has considerable influence on the properties of the plasma. For example, the electron density obtained for a given hf power density deposited into the plasma is usually higher at microwave than at radio frequencies (rfs). This paper reviews a series of experiments at the Université de Montréal designed to investigate the influence of ω on the power balance between the hf field and the plasma, and the plasma processing of materials. For the two particular etching and deposition processes which are described here, the ‘‘optimum’’ frequency (at which the process is most efficient) appears to be in the range between 50 and 100 MHz. This suggests that converting a plasma process from 13.56 to 2450 MHz does not necessarily lead to the greatest possible process enhancement, and that optimization may require the plasma reactor to be constructed in such a way as to allow the excitation frequency to be changed. To provide insight into these results, the most recent models dealing with the influence of ω on the electron energy distribution are reviewed and extended to calculate parameters that can be compared with our experimental data.

An X-ray and neutron reflectometry study of ‘PEG-like’ plasma polymer films

“…The low protein adsorption in this study compared with those reported in the current study could be attributed to a higher C-O component (84%), lower protein concentrations and differences in plasma-processing parameters such as the pulsed plasma conditions and the use of a tetraglyme monomer [30]. Previous studies have shown that tri-and tetraglyme plasma polymer films are extremely effective in reducing surface protein adsorption [15,20]. , for which the oxygen content is higher (33% O, 67% C).…”

“…The 20 and 50 W films were also measured against aqueous solution using NR, with the neutron beam reflecting from the film/water surface. Three different solvents ('contrasts') were used for the 20 Changing the deuteration level of the solution changes the refractive index of the water and therefore the scattering contrast of the system. An analysis identical to that carried out on the dry films was performed.…”

“…It is therefore highly unlikely that low-fouling plasma polymer films produced via the plasma polymerization of 'glyme' monomers will exactly reproduce the polymer surface chemistry generated from the more commonly used PEG polymer graft surfaces [9,[17][18][19]. Plasma polymer chemistries generated from a particular monomer may vary substantially depending on the operational conditions used (reactor geometry, monomer flow rate, pressure, mode and the strength of power delivery and frequency) [20].…”

Correlation of Growth and Surface Properties of Poly(\(p\)-xylylenes) to Reaction Conditions

“…The reason for this different behavior, which is reflected in surface properties (see below), is still an area of current research. Perhaps the molecules are subjected to the higher electromagnetic field and the static DC field across the hot electrode in RF discharges and are consequently destroyed more readily than by microwave excitation [41,42] Figure 14. Detail of the IR spectrum of PECVD parylene N and CVD parylene N.…”

Transport properties of nanocrystalline silicon and silicon–germanium

“…[24,25,26]. In this section we first briefly review the theory behind VHF PECVD, its advantages and then present the specific results from literature obtained in nc-Si material.…”