High-Frequency Measurements of Plasma Parameters in Electron Cyclotron Resonance Plasma Etchers.

High-frequency measurements of plasma parameters used in circuit model simulation were carried out to analyze charging damage. The bulk plasma impedance was measured by varying the bias voltage of probes with an impedance analyzer. The sheath condenser and the sheath diode characteristics were derived by fitting parameters in such a way that current–voltage (I–V) Lissajous' waveforms in the simulation agree with those in the measurement obtained using one spherical probe. The accuracy of the circuit model simulation improved by introducing the correction coefficients of the plasma parameters, which were derived by comparison between the calculated value and the measured one. Therefore, the circuit model simulation results agreed closely with the experimental results obtained using a charging damage measurement electrode. Both methods are effective for investigating the reduction of charging damage, in particular, of the etcher used for 12 inch wafers.