Mechanisms of Surface Reaction in Fluorocarbon Dry Etching of Silicon Dioxide-An Effect of Thermal Excitation

Abstract
Ion bombardment-induced thermal reaction between a fluorocarbon adlayer and a SiO2 surface in a reactive-ion-etching (RIE) environment which was simulated in an ultrahigh-vacuum thermal desorption mass spectroscopy (TDS) apparatus has been studied. The RIE-induced fluorocarbon chemisorbed layer, covering the SiO2 surface, was observed to be thermally stimulated to react chemically with the SiO2 in the TDS apparatus with an activation energy of approximately 1.9 eV. A terminal group, chemisorbed at the adlayer/SiO2 interface, could be an active participant in the thermal reaction. This observation indicates the possibility that chemical sputtering could occur in the actual RIE through a thermal excitation step, induced by ion bombardment. A significant difference in the RIE-induced mixing of fluorine atoms between SiO2 and Si also appeared in their TDS spectra.

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