Time-resolved electrostatic probe studies of a pulsed inductively-coupled plasma

We report a systematic study of a pulsed 13.56 MHz transformer-coupled plasma over a range of frequencies from 200 Hz to 10 kHz using electrostatic probes. The time-resolved plasma density and electron temperature from the double-probe analysis were compared with single Langmuir probe results using both the orbital-motion-limited and radial-motion theories with sheath displacement corrections. The results were compared to a spatially-averaged model. Our experiments and analysis show that the double probes can be used reliably in pulsed plasma measurements. The good agreement: between the equivalent resistance: method and the nonlinear regression method indicates that the equivalent resistance method, which is faster and easier to automate, can be used effectively to analyse the double-probe data. The transient behaviours of the plasma density and electron temperature, although complicated, are in accord with the simple model of the discharge. The plasma density and the electron temperature can be decoupled in a pulsed plasma by adjusting the pulse parameters. This decoupling suggests that a pulsed plasma source can provide additional control for ion-assisted or neutral-assisted etching and deposition.