Ion control for a plasma source
One embodiment is directed to a plasma source comprising a cavity and at least first and second electrodes. The plasma source is configured to, during a first portion of each cycle, bias the first electrode as a cathode and use the second electrode as an anode, during a second portion of each cycle, apply an ion flush bias to the first and second electrodes, during a third portion of each cycle, bias the second electrode as a cathode and use the first electrode as an anode, and during a fourth portion of each cycle, apply an ion flush bias to the first and second electrodes. Other embodiments are disclosed.
1. A plasma source comprising:
at least first and second electrodes;
wherein the plasma source is coupled to a controller configured to:
during a first portion of each cycle, bias the first electrode as a cathode and use the second electrode as an anode;
during a second portion of each cycle, apply an ion flush bias to the first and second electrodes;
during a third portion of each cycle, bias the second electrode as a cathode and use the first electrode as an anode; and
during a fourth portion of each cycle, apply an ion flush bias to the first and second electrodes.
2. The plasma source of claim 1 , wherein the plasma source is coupled to one or more direct current power supplies.
3. The plasma source of claim 1 , wherein the the plasma source is coupled to a switching unit.
4. The plasma source of claim 1 , wherein the plasma source includes a racetrack or cylindrically shaped wall defining a cavity, and wherein each of the first and second electrodes follows the wall shape.
5. The plasma source of claim 1 , further comprising at least one magnet.
6. The plasma source of claim 1 , wherein each cycle comprises a pulse cycle;
wherein the first portion of each cycle comprises a first pulse during which the controller is configured to bias the first electrode as a cathode and use the second electrode as an anode;
wherein the second portion of each cycle comprises a second pulse during which the controller is configured to apply an ion flush bias to the first and second electrodes;
wherein the third portion of each cycle comprises a third pulse during which the controller is configured to bias the second electrode as a cathode and use the first electrode as an anode; and
wherein the fourth portion of each cycle comprises a fourth pulse during which the controller is configured to apply an ion flush bias to the first and second electrodes.
7. The plasma source of claim 1 , wherein the ion flush bias applied to the first and second electrodes during the second and further portions of each cycle comprise a positive ion flush bias that is used to increase the ion flux toward the substrate that is created using the plasma source.
8. The plasma source of claim 1 , wherein the ion flush bias applied to the first and second electrodes during the second and further portions of each cycle comprise a negative ion flush bias that is used to decrease the ion flux toward the substrate that is created using the plasma source.
9. The plasma source of claim 1 , wherein the plasma source defines a cavity having at least one inlet via which gases enter the cavity.
10. The plasma source of claim 9 , wherein a discharge aperture is formed in the cavity.
11. A deposition system comprising:
a substrate;
a plasma source configured to discharge an ion beam onto the substrate, the plasma source comprising:
at least first and second electrodes; and
a controller configured to:
during a first portion of each cycle, bias the first electrode as a cathode and use the second electrode as an anode;
during a second portion of each cycle, apply an ion flush bias to the first and second electrodes;
during a third portion of each cycle, bias the second electrode as a cathode and use the first electrode as an anode; and
during a fourth portion of each cycle, apply an ion flush bias to the first and second electrodes.
12. The system of claim 11 , further comprising at least one direct current power supply.
13. The system of claim 11 , wherein the ion flush bias applied to the first and second electrodes during the second and further portions of each cycle comprise one of:
a positive ion flush bias that is used to increase the ion flux toward the substrate that is created using the plasma source; and
a negative ion flush bias that is used to decrease the ion flux toward the substrate that is created using the plasma source.
14. The system of claim 12 , further comprising a switching unit that comprises:
a first switch that is configured to selectively couple the first electrode to either a positive output of the direct current power supply or a negative output of the direct current power supply;
a second switch that is configured to selectively couple the second electrode to either the positive output of the direct current power supply or the negative output of the direct current power supply.