Synchronized pulsing of plasma processing source and substrate bias
Systems and methods for plasma processing are disclosed. A method includes applying power to a plasma processing chamber during a first processing step and generating, during the first processing step, a first plasma sheath voltage between a substrate and a plasma. During a second processing step (that follows the first processing step), power is applied to the plasma processing chamber and a different plasma sheath voltage is applied between the substrate and the plasma.
1. A method for plasma processing, the method comprising:
applying continuous wave power to a plasma processing chamber during a first processing step;
applying, during the first processing step, an asymmetric periodic voltage waveform to a substrate support to produce a first plasma sheath voltage between a substrate and a plasma;
applying pulsed power to the plasma processing chamber during a second processing step, wherein the second processing step follows the first processing step; and
applying, during the second processing step, a different asymmetric periodic voltage waveform to the substrate support to produce a different plasma sheath voltage between the substrate and the plasma that has a magnitude that is different than a magnitude of the first plasma sheath voltage during the first processing step.
2. The method of claim 1 , wherein a voltage of the pulsed power during the second processing step is lower than a voltage of the continuous wave power during the first processing step.
3. The method of claim 1 , wherein applying the different asymmetric periodic voltage waveform during the second processing step includes applying the different asymmetric periodic voltage waveform during the second processing step to produce a range of sheath voltages during the second processing step.
4. The method of claim 1 , including providing current to a support for the substrate that is at least one of greater than or less than ion current of ions impacting a surface of the substrate.
5. A plasma processing system, the system comprising:
a plasma processing chamber;
an excitation source configured to apply power to the plasma processing chamber to produce a plasma in the plasma processing chamber;
a bias supply configured to apply and modify an asymmetric periodic voltage waveform to a substrate support to modify a sheath voltage between the plasma and a substrate within the plasma processing chamber;
at least one controller configured to synchronize operation of the excitation source and the bias supply during each of a plurality of processing steps, wherein the at least one controller is configured to:
control the excitation source to apply power during a first processing step as continuous wave power;
control the excitation source to apply power during a second processing step as pulsed power; and
control the bias supply to produce a sheath voltage during the second processing step that is different in magnitude than the sheath voltage during the first processing step.
6. The plasma processing system of claim 5 , wherein the at least one controller is configured to control the excitation source to apply a voltage of the power during the second processing step at a lower level than a voltage of the power during the first processing step.
7. The plasma processing system of claim 5 , wherein the at least one controller is configured to control the bias supply to produce a range of sheath voltages during the second processing step.
8. The plasma processing system of claim 7 , wherein the at least one controller is configured to control the bias supply to provide current to a support for the substrate that is at least one of greater than or less than ion-current of ions impacting a surface of the substrate to produce the range of sheath voltages.
9. The plasma processing system of claim 5 , wherein the at least one controller includes at least one of a processor or a field programmable gate array, and wherein the at least one controller includes a non-transitory computer-readable medium comprising instructions stored thereon, for execution by the processor, or for configuring the field programmable gate array, to:
control the excitation source to apply the power during the first processing step as continuous wave power;
control the excitation source to apply the power during the second processing step as pulsed power; and
control the bias supply to produce the sheath voltage during the second processing step that is different in magnitude than the sheath voltage during the first processing step.
10. A non-transitory computer-readable medium comprising instructions stored thereon, for execution by a processor, or for configuring a field programmable gate array, to perform plasma processing, the instructions including instructions to:
apply continuous wave power to a plasma processing chamber during a first processing step;
apply, during the first processing step, an asymmetric periodic voltage waveform to a substrate support to produce a first plasma sheath voltage between a substrate and a plasma;
apply pulsed power to the plasma processing chamber during a second processing step, wherein the second processing step follows the first processing step; and
apply, during the second processing step, a different asymmetric periodic voltage waveform to the substrate support to produce a different plasma sheath voltage between the substrate and the plasma that has a magnitude that is different than a magnitude of the first plasma sheath voltage during the first processing step.
11. The non-transitory computer-readable medium of claim 10 , wherein the instructions include instructions to apply a voltage of the pulsed power during the second processing step that is lower than a voltage of the continuous wave power during the first processing step.
12. The non-transitory computer-readable medium of claim 10 , including instructions to apply the different asymmetric periodic voltage waveform during the second processing step to generate a range of sheath voltages during the second processing step.
13. The non-transitory computer-readable medium of claim 10 including instructions to provide current to the substrate support that is at least one of greater than or less than ion current of ions impacting a surface of the substrate to generate a range of sheath voltages during the second processing step.
14. The non-transitory computer-readable medium of claim 10 including instructions to provide current to the substrate support that is at least one of greater than or less than ion current of ions impacting a surface of the substrate to generate a range of sheath voltages during the first processing step.