Silicon oxide particle formation in RF plasmas investigated by infrared absorption spectroscopy and mass spectrometry

Abstract

In situ Fourier transform infrared absorption spectroscopy has been used to study the composition of particles formed and suspended in radio-frequency discharges of silane-oxygen-argon gas mixtures. The silane gas consumption was observed by infrared absorption. The stoichiometry of the produced particles depends on the silane flow rate and was compared with commercial colloidal silica. A small proportion of silane gas produces nanometric stoichiometric particles whereas a large proportion produces larger under-stoichiometric particles. Absorption spectroscopy was sufficiently sensitive to reveal particles too small to be visually observed by laser light scattering. Post-oxidation of hydrogenated silicon particles trapped in an argon plasma was obtained by adding oxygen. Mass spectrometry of negative and positive ions showed an extensive range of ionic clusters which may be at the origin of the observed particle formation. A model based on an iterative reaction sequence gives a good agreement with the measured positive ion mass spectrum.

Nanoparticle production from HMDSO in atmospheric pressure argon‐oxygen plasma

“…Nanoparticle deposition on powders using low pressure non‐equilibrium plasma has been demonstrated in the past . As precursors silane and organosilicon monomers have been investigated since they possibly yield silica‐like, inert films and particles . However, working at low pressure has major drawbacks: investment and operation costs of vacuum equipment are high and the implementation of vacuum processes in continuous production lines are not always possible.…”

Plasma‐Enhanced CVD for Particle Synthesis Using Circulating Fluidized Bed Technology

“…Another part is lost from the gas phase by powder formation. [18] Desorbed species, powder, and volatile products are pumped out of the reaction chamber. The plasma process is characterized by a high fragmentation degree of the precursor prior to deposition.…”

Correlation Between the Electrical and Optical Properties of an Atmospheric Pressure Plasma During Siloxane Coating Deposition

“…12). It has previously been reported that larger, non-stoichiometric particles are generally formed at high precursor flow rates while nano-scale stoichiometric particles are formed at lower flow rates [47]. With increasing applied power, there are increased concentrations of active species in the plasma, as indicated by both multi-peak behaviour and increased emission intensity.…”