Hydrocarbon plasma emission as a means to monitor plasma polymerization, revisited

Abstract

The degree of aromaticity of toluene plasma polymer is shown to decrease with decreasing toluene flow rate into the plasma (constant rf power). Optical emission spectroscopy (OES) of the plasma is predictive; a plasma emitting a higher relative benzyl radical signal results in the deposition of a more aromatic plasma polymer. Such results have been earlier reported in the literature. However, in this work the geometry of OES observation assured that only plasma emissions from the vicinity of the deposition site were observed. Under these conditions it is found that plasma pressure must be kept constant for the predictive nature of OES results to hold.