Characterization of a high-frequency inductively coupled plasma source

We report the experimental results of a 27.12 MHz inductively coupled plasma source for next generation dry etching. The new source is designed to improve the plasma density uniformity for large-area processing. The key techniques of this new source are the reduction of the inductance of the antenna system in parallel connection and the induction of LC resonance with external capacitance variation. An external variable capacitor is connected in series to an outer coil to obtain a high level of plasma uniformity. We can control the radial plasma density with 5% uniformity by only varying the external capacitance. The electron density varies linearly with the discharge power and increases monotonically with pressure. The electron density in 27.12 MHz is lower than that in 13.56 MHz at the same discharge power. An essential difference was found in the effective electron temperature. The lower electron temperature in 27.12 MHz is obtained from EEPFs. The electron temperature was 1.5 eV–2.5 eV.