Pixelated capacitance controlled ESC
Implementations described herein provide a chucking circuit for a pixilated electrostatic chuck which enables both lateral and azimuthal tuning of the RF coupling between an electrostatic chuck and a substrate placed thereon. In one embodiment, a chucking circuit for an electrostatic chuck (ESC) has one or more chucking electrodes disposed in a dielectric body of the ESC, a plurality of pixel electrodes disposed in the dielectric body, and a chucking circuit having the one or more chucking electrodes and the plurality of pixel electrodes, the chucking circuit operable to electrostatically chuck a substrate to a workpiece support surface of the ESC, the chucking circuit having a plurality of secondary circuits, wherein each secondary circuit includes at least one capacitor of a plurality of capacitors, each secondary circuit is configured to independently control an impedance between one of the pixel electrodes and a ground.
1. A chucking circuit for an electrostatic chuck (ESC), the chucking circuit comprising:
one or more chucking electrodes disposed in a dielectric body of the ESC;
a plurality of pixel electrodes disposed in the dielectric body; and
a chucking circuit comprising the one or more chucking electrodes and the plurality of pixel electrodes, the chucking circuit operable to electrostatically chuck a substrate to a workpiece support surface of the ESC, the chucking circuit having a plurality of secondary circuits, wherein each secondary circuit includes at least one capacitor of a plurality of capacitors, each secondary circuit is configured to independently control an impedance between one of the pixel electrodes and a ground.
2. The chucking circuit of claim 1 , further comprising:
a pixel controller configured to independently open and close the secondary circuits.
3. The chucking circuit of claim 1 , wherein the plurality of capacitors further comprise:
a plurality of variable capacitors; and
a plurality of fixed capacitors, wherein the plurality of capacitors are coupled through decoupling resistors to a thin-film transistor (TFT).
4. The chucking circuit of claim 3 , wherein the variable capacitors may provide between about 0 pF to about 3.4 pF of capacitance and each fixed capacitor may provide between about 0.5 pF to about 74 pF of total capacitance to the variable capacitor and wherein the decoupling resistors, disposed between the TFT and the capacitors may individually provide about 5 ohms of resistance.
5. The chucking circuit of claim 4 , wherein the capacitance between the substrate and the ESC is about 220 pF to about several hundred pF.
6. The chucking circuit of claim 3 , wherein the variable capacitors are mechanically adjustable.
7. The chucking circuit of claim 3 , wherein the variable capacitors are electrically adjustable.
8. The chucking circuit of claim 3 , wherein the variable capacitors are RF variable capacitors.
9. The chucking circuit of claim 1 , wherein the capacitors are about 3.2 mm×3.2 mm×0.53 mm or smaller.
10. The chucking circuit of claim 1 , wherein an impedance of a first circuit of the plurality of secondary circuits is different than a second circuit of the plurality of secondary circuits.
11. The chucking circuit of claim 1 , wherein a local variation in the impedance across the workpiece support surface of the ESC is less than 10%.
12. The chucking circuit of claim 1 , wherein at least one of the capacitors is a MEMS capacitor.