Comparison of distributions of etching rate and calculated plasma parameters in dual-frequency capacitively coupled plasma

Abstract

Abstract We measured the etching rates of SiO2 and Si in dual-frequency excited CF4 plasma and compared the etching rates with the radical species distribution calculated by plasma simulation. The etching rates of SiO2 and Si at the wafer edge became higher than those at the wafer center, and the etching rate of Si distributed uniformly without bias voltage. In the simulation, the calculation model was calibrated on the basis of the measured (electron density). Assuming that CF3 + contributes to SiO2 and Si etching, and F contributes to Si etching without bias voltage, the radical fluxes flowing into the wafer were calculated by plasma simulation. The fluxes of CF3 + and CF2 became higher at the edge, and the F flux distribution was uniform without the bias voltage. It was shown that the distributions of the etching rate in the experiment and radical flux that contributes to etching in the simulation were in agreement.