Plasma polymerization by magnetron glow discharge. II. Effect of magnetic field on chemical characteristics of plasma polymers of tetrafluoroethylene revealed by electron spectroscopy for chemical analysis

Abstract

Plasma polymerizations of tetrafluoroethylene (TFE) by magnetron glow discharges were investigated by varying the magnetic field of a magnetron electrode system. Polymer deposition rates at two strategically selected positions in the electrode space and chemical characteristics of deposited films revealed by electron spectroscopy for chemical analysis (ESCA) were studied as functions of a magnetic field. It was found the presence of a magnetic field influences the spatial distribution of deposition rates and chemical characteristics of the deposited polymers. The intensity, width, and the relative location of the intense glow (in the form of a ring) with respect to the electrode surface vary with the magnetic field strength and the discharge voltage. Because the intense glow is highly localized (only in a ring shape adhering close to the electrode surface), the remaining glow discharge, which fills the majority of the interelectrode space, becomes a weak, but uniform field for plasma polymerization. This situation is similar to the tail-flame portion of a rf tubular reactor. In the presence of a magnetic field in the range investigated and at a relatively low level of discharge wattage, plasma polymerization yields films with three-dimensional networks comprised of relatively long segments and lesser amounts of quaternary carbons. The overall characteristics of plasma polymers, however, are similar to those formed without a magnetic field.