RF tuning method for an RF plasma reactor using frequency servoing and power, voltage, current or DI/DT control

摘要

In an RF plasma reactor including a reactor chamber with a process gas inlet, a workpiece support, an RF signal applicator facing a portion of the interior of the chamber and an RF signal generator having a controllable RF frequency and an RF signal output coupled to an input of the RF signal applicator, the invention tunes the RF signal generator to the plasma-loaded RF signal applicator by sensing an RF parameter at the RF signal generator or at the RF signal applicator and then adjusting the frequency of the RF signal generator so as to optimize the parameter. The invention further controls the RF signal generator output magnitude (power, current or voltage) by optimizing the value of the same RF parameter or another RF parameter. The reactor preferably includes a fixed tuning circuit between the RF signal generator and the RF signal applicator.