Frequency tuning for pulsed radio frequency plasma processing

摘要

This disclosure describes systems, methods, and apparatus for pulsed RF power delivery to a plasma load for plasma processing of a substrate. In order to maximize power delivery, a calibration phase using a dummy substrate or no substrate in the chamber, is used to ascertain a preferred fixed initial RF frequency for each pulse. This fixed initial RF frequency is then used at the start of each pulse during a processing phase, where a real substrate is used and processed in the chamber.

主权项

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.