Apparatus and system for modulated plasma systems
Plasma processing systems and methods are disclosed. The plasma processing system includes a high-frequency generator configured to deliver power to a plasma chamber and a low-frequency generator configured to deliver power to the plasma chamber. A filter is coupled between the plasma chamber and the high-frequency generator, and the filter suppresses mixing products of high frequencies produced by the high-frequency generator and low frequencies produced by the low-frequency generator.
1. A plasma processing system comprising:
a high-frequency generator configured to deliver power to a plasma chamber as a multi-state waveform;
a low-frequency generator configured to deliver power to the plasma chamber;
a filter configured to suppress power mixing products to limit variation of a time-varying load reflection coefficient presented to the high frequency generator; and
a frequency-tuning subsystem configured to adjust, within each state, a frequency of the multi-state waveform based upon inter-pulse measurements of the multi-state waveform, wherein a frequency within a particular state is controlled based upon measurements of identical time slots of sequential pulses of the particular state to adjust an impedance presented to the high-frequency generator.
2. The plasma processing system of claim 1 , wherein measurements of identical timeslots of sequential pulses are combined with measurements of time slots adjacent to those time slots.
3. A plasma processing system comprising:
a high-frequency generator configured to deliver power to a plasma chamber;
a low-frequency generator configured to deliver power to the plasma chamber;
a filter configured to suppress power mixing products to limit variation of a time-varying load reflection coefficient presented to the high frequency generator; and
a frequency-tuning subsystem configured to adjust a frequency of the high-frequency generator to adjust an impedance presented to the high-frequency generator;
wherein the frequency-tuning subsystem is configured to adjust the frequency of the power by:
delivering power at a selected frequency for at least 90% of a total time;
delivering power at a test frequency during test periods, wherein the test periods are no longer than 10% of the total time, wherein a value of the test frequency changes from test period to test period; and
changing a value of the selected frequency to the value of the test frequency if the impedance presented to the high-frequency generator is closer to a target impedance when the high-frequency generator is delivering power at the test frequency.
4. The plasma processing system of claim 3 , wherein the same test frequency is visited multiple times, each time adjusting the power delivered to the plasma load towards a desired power level.
5. A plasma processing system comprising:
a high-frequency generator configured to deliver power to a plasma chamber as a multi-state waveform;
a low-frequency generator configured to deliver power to the plasma chamber;
a filter coupled between the plasma chamber and the high frequency generator, the filter including two or more helical resonators connected in parallel;
a time delay element between the filter and the plasma chamber; and
a frequency-tuning subsystem configured to adjust, within each state, a frequency of the multi-state waveform based upon inter-pulse measurements of the multi-state waveform, wherein a frequency within a particular state is controlled based upon measurements of identical time slots of sequential pulses of the particular state to adjust an impedance presented to the high-frequency generator.
6. The plasma processing system of claim 5 wherein the time delay element is a fixed time delay element.
7. The plasma processing system of claim 5 wherein the time delay element is a variable time delay element.
8. The plasma processing system of claim 5 , wherein the high-frequency generator is configured to apply a multi-state waveform and the frequency-tuning subsystem is configured to control the frequency of the multi-state waveform based upon inter-pulse measurements of the multi-state waveform.
9. The plasma processing system of claim 8 , wherein the frequency-tuning subsystem is configured to adjust the frequency of the multi-state waveform based upon inter-pulse measurements that are measurements of identical time slots of sequential pulses.
10. The plasma processing system of claim 9 , wherein measurements of identical timeslots of sequential pulses are combined with measurements of time slots adjacent to those time slots.
11. A plasma processing system comprising:
a high-frequency generator configured to deliver power to a plasma chamber;
a low-frequency generator configured to deliver power to the plasma chamber;
a filter coupled between the plasma chamber and the high frequency generator, the filter including two or more helical resonators connected in parallel;
a time delay element between the filter and the plasma chamber; and
a frequency-tuning subsystem configured to adjust a frequency of the high-frequency generator to adjust an impedance presented to the high-frequency generator;
wherein the frequency-tuning subsystem is configured to adjust the frequency of the power by:
delivering power at a selected frequency for at least 90% of a total time;
delivering power at a test frequency during test periods, wherein the test periods are no longer than 10% of the total time, wherein a value of the test frequency changes from test period to test period; and
changing a value of the selected frequency to the value of the test frequency if the impedance presented to the high-frequency generator is closer to a target impedance when the high-frequency generator is delivering power at the test frequency.
12. The plasma processing system of claim 11 , wherein the same test frequency is visited multiple times, each time adjusting the power delivered to the plasma load towards a desired power level.
13. A plasma processing system comprising:
a high-frequency generator configured to apply a multi-state waveform to a plasma chamber;
a low-frequency generator configured to deliver power to the plasma chamber;
a filter configured to suppress power mixing products to limit variation of a time-varying load reflection coefficient presented to the high frequency generator; and
means for adjusting, within each state, a frequency of the multi-state waveform based upon inter-pulse measurements of the multi-state waveform, wherein a frequency within a particular state is controlled based upon measurements of identical time slots of sequential pulses of the particular state to adjust an impedance presented to the high-frequency generator.
14. The plasma processing system of claim 13 , wherein the means for adjusting the frequency of the multi-state waveform comprises means for adjusting the frequency of the multi-state waveform based upon inter-pulse measurements that are measurements of identical time slots of sequential pulses.