Common electrostatic chuck for differing substrates
An apparatus, methods and controllers for electrostatically chucking varied substrate materials are disclosed. Some embodiments of the disclosure provide electrostatic chucks with variable polarity and/or voltage. Some embodiments of the disclosure provide electrostatic chucks able to operate as monopolar and bipolar electrostatic chucks. Some embodiments of the disclosure provide bipolar electrostatic chucks able to compensate for substrate bias and produce approximately equal chucking force at different electrodes.
1. An electrostatic chuck comprising:
a first electrode powered by a first power supply with a first power, the first power having a first voltage and a positive or negative polarity with reference to a substrate;
a second electrode powered by a second power supply with a second power, the second power having a second voltage and a positive or negative polarity with reference to the substrate;
a center-tap voltage feedback; and
a controller connected to the first power supply, the second power supply, and the center-tap voltage feedback, the controller configured to control one or more of the polarity of the first power; the first voltage; the polarity of the second power; or the second voltage, and to balance the first voltage and the second voltage with reference to the substrate.
2. The electrostatic chuck of claim 1 , wherein the first voltage and the second voltage are less than or equal to about 3 kV.
3. The electrostatic chuck of claim 1 , wherein the polarity of the first power and the second power are the same.
4. The electrostatic chuck of claim 3 , wherein the first voltage and the second voltage are about the same.
5. The electrostatic chuck of claim 1 , wherein the polarity of the first power and the second power are different.
6. The electrostatic chuck of claim 1 , wherein the polarity of the first power and the second power are the same, and the center-tap voltage feedback is isolated from the first power supply and the second power supply.
7. The electrostatic chuck of claim 1 , wherein the polarity of the first power and the second power are different, and the center-tap voltage feedback is referenced to a common ground of the first power supply and the second power supply.
8. The electrostatic chuck of claim 1 , wherein the center-tap voltage feedback comprises an RF frequency filter.
9. The electrostatic chuck of claim 8 , wherein the RF frequency filter operates at one or more of 13.56 MHz or 60 MHz.
10. A method of chucking a substrate, the method comprising:
placing a substrate in proximity to an electrostatic chuck, the electrostatic chuck comprising:
a first electrode powered with a first power by a first power supply, the first power having a first voltage and a positive or negative polarity with reference to the substrate;
a second electrode powered with a second power by a second power supply, the second power having a second voltage and a positive or negative polarity with reference to the substrate opposite of the polarity of the first power; and
a center-tap voltage feedback; and
activating the electrostatic chuck;
exposing the substrate to a plasma;
measuring a bias between the substrate and the electrostatic chuck to provide a C-T voltage; and
offsetting the first voltage and the second voltage by the C-T voltage to balance a chucking force of the first electrode and the second electrode.
11. The method of claim 10 , wherein the center-tap voltage feedback comprises an RF frequency filter.
12. The method of claim 11 , wherein the RF frequency filter operates at one or more of 13.56 MHz or 60 MHz.
13. The method of claim 10 , wherein the center-tap voltage feedback is operated intermittently.
14. The method of claim 10 , wherein the polarity of the first power and the second power are the same and the center-tap voltage feedback is isolated from the first power supply and the second power supply.
15. The method of claim 10 , wherein the polarity of the first power and the second power are the same and the first voltage and the second voltage are about the same.
16. The method of claim 10 , wherein the polarity of the first power and the second power are different, and the center-tap voltage feedback is referenced to a common ground of the first power supply and the second power supply.
17. A method of chucking a substrate, the method comprising:
placing a first substrate comprising a monopolar material or a bipolar material in proximity to an electrostatic chuck, the electrostatic chuck comprising:
a first electrode powered with a first power by a first power supply, the first power having a first voltage and a positive or negative polarity with reference to a substrate; and
a second electrode powered with a second power by a second power supply, the second power having a second voltage and a positive or negative polarity with reference to the substrate; and
activating the electrostatic chuck;
dechucking the first substrate;
placing a second substrate comprising a monopolar material or a bipolar material different from the first substrate in proximity to the electrostatic chuck;
switching the polarity of the first power supply or the second power supply; and
activating the electrostatic chuck,
wherein when the first power and the second power have matching polarities the first substrate comprises a monopolar material and when the first power and the second power have opposite polarities the first substrate comprises a bipolar material.
18. The method of claim 17 , wherein when the first substrate comprises a monopolar material, the first voltage and the second voltage are about the same.