What is the difference between VI probe and the plasma metrology system Hercules®?
A VI probe delivers voltage V, RF current I, and the phase angle φ between V and I outside the chamber. From this data one can calculate resistance using an simple eqivalent circuit with series circuit of capacitance C and resistance R. A VI probe delivers NO plasma parameters, just parameters from somewhere outside the chamber. That means FDC for the RF subsystem YES, process control NO.
