Radio frequency (RF) pulsing impedance tuning with multiplier mode

A method for processing a substrate in a plasma enhanced substrate processing system using multi-level pulsed RF power, comprising:

• receiving a process recipe for processing the substrate that includes a plurality of pulsed RF power waveforms from a plurality of RF generators, wherein the plurality of RF generators includes a master RF generator and one or more slave RF generators;
• using the master RF generator to generate a transistor-transistor logic (TTL) signal having a base frequency and a first duty cycle;
• setting a multiplier for each RF generator, wherein the multiplier is a multiple of the base frequency;
• dividing the first duty cycle into a high level interval and a low level interval;
• determining a frequency command set for each RF generator and sending the frequency command set to each RF generator, wherein the frequency command set includes a frequency set point for each RF generator, and wherein determining the frequency command set includes:
• calculating a high average impedance value across the high level interval and a low average impedance value across the low level interval;
• calculating a target impedance based on the high average impedance value and the low average impedance value;
• tuning one or more RF match networks to the target impedance;
• and
• adjusting a frequency or power provided by at least one of the plurality of RF generators to reduce at least one of the high average impedance value or the low average impedance value;
• and
• providing the plurality of pulsed RF power waveforms from the plurality of RF generators to a process chamber according to the frequency command set sent to each RF generator.

A substrate processing system comprising:

• a plurality of RF generators configured to provide a plurality of RF power waveforms to a process chamber during a first duty cycle, wherein the plurality of RF generators include a master RF generator and one or more slave RF generators;
• a pulse controller coupled to the plurality of RF generators;
• at least one match network coupled to each of the plurality of RF generators, the process chamber, and the pulse controller, wherein the at least one match network includes at least one measuring device configured to measure reflected power or impedance for the plurality of RF power waveforms and at least one variable match component;
• wherein at least one of the pulse controller or the at least one match network is configured to:
• receive a process recipe for processing the substrate;
• set a multiplier for at least one of the plurality of RF generators, wherein the multiplier is a multiple of a base frequency of a TTL signal created by the master RF generator;
• divide a first duty cycle of the TTL signal into a high level interval and a low level interval;
• determine a frequency command set for each RF generator by calculating a target impedance based on average impedance values and tuning one or more RF match networks to the target impedance and send the frequency command set to each RF generator, wherein the frequency command set includes a frequency set point for each RF generator;
• and
• provide an RF power waveform from each RF generator to a process chamber according to the frequency command set sent to each RF generator.