The discussions in the previous pages were referring to DC plasma
AC plasma however is used more frequently than DC plasma due to increased efficiency
The applied electri field is in this case an oscillating field, therefore the charged particles will have a harmonic motion described by this equation:
Because the motion is harmonic no power is absorbed by a free electron
However, due to collisions, the particles motion is randomised, (not a perfect harmonic) and power is absorbed from the RF source
Thus plasma is ignited only at high pressure, when there are sufficient collisions to randomise the particles movement
Substrate preparation
