Roles of Ions and Radicals in Silicon Oxide Etching

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Abstract
Thermally stimulated desorption and X-ray photoelectron spectroscopy were used to study the adsorptive condition of reactive-ion-etched SiO2 and PSG surfaces. Its relationship to the different reactivity between SiO2 and PSG under the condition of highly polymerized fluorocarbon plasma was discussed. The reaction process of radicals under the thermally excited condition was also investigated in a microwave-excited downstream reactor. The C, F molecules which covered the oxide surfaces as etching species during RIE were found to be chemisorbed, and as residues, they were adsorbed weakly. It was also found that oxygen atoms have the effect of decreasing the activation energy of the spontaneous reaction with the oxide surfaces in the fluorocarbon plasma.