Characteristics of VHF excited hydrogen plasmas using a ladder-shaped electrode

A VHF excited hydrogen plasma was produced with a ladder-shaped electrode whose excitation frequency ranged up to 100 MHz for gas pressures of 40–200 mTorr and the plasma parameters were measured with a Langmuir probe. When the excitation frequency was increased, the electron density increased and the electron temperature decreased. The pressure dependence of the electron temperature at excitation frequencies of 65 and 100 MHz was different from the usual relationship: the electron temperature tended to increase with increasing pressure.