A Chemical Dry Etching of Si and SiO2 Substrates by F atoms in a Discharge Flow

Abstract

F atoms were generated by a low power microwave discharge of various Ar/CF4 mixtures in a fast discharge flow. They were used for Si and SiO2 etching at room temperature. The variations of the relative concentration of F as functions of various etching parameters were monitored by observing CH( A2Δ– X2Π r) emission resulting from the Ar(3P0,2)/CH3 reaction. The emission spectra of Ar/CF4 mixtures in the microwave discharge indicated that CF4 was decomposed into C and F atoms in the discharge region because of the lack of emissions from CF*, CF2*, and CF3*. The etching rates of Si and SiO2 were about 700 and 70 Å/min, respectively, at a microwave power of 100 W, an Ar flow rate of 3000 sccm, a CF4 flow rate of 250 sccm, a total pressure of 0.23 Torr and a distance between the center of discharge and the substrate of 12 cm.