Patent ID: 9544987
Date: 2017-01-10
CPC Classifications: H01J,H05H

Claim:
1. A method of selecting a fixed initial RF frequency for each of a plurality of RF pulses provided to a plasma load, the method comprising: providing pulsed RF power to a plasma load, where each pulse comprises RF power having a controllable frequency, and where a plasma having the plasma load interacts with a dummy substrate, or no substrate, in a plasma chamber; tuning an initial RF frequency for each pulse in a string of pulses, pulse to pulse, in a calibration process, by minimizing a difference between a characteristic indicative of the pulsed RF power at a start of each pulse and a desired characteristic of the pulsed RF power at a start of each pulse until the difference between the characteristic for a start to two consecutive pulses is below a threshold; then selecting the initial RF frequency as a fixed initial RF frequency for use in a processing run using a real substrate; and tuning the RF frequency during processing within each pulse but returning to the fixed initial RF frequency at a start of each pulse.