Electrostatic chuck and method of operation for plasma processing
An electrostatic chuck (ESC) for holding a workpiece in a plasma processing chamber, where the ESC includes a monolithic insulating substrate with a top surface; a plurality of electrodes embedded in the insulating substrate, the plurality of electrodes being in a multipolar configuration to receive multiple DC bias signals from a first power supply circuit; and a radio frequency (RF) electrode embedded in the insulating substrate, the plurality of electrodes being located between the top surface and the RF electrode, the RF electrode including a contact node configured to be coupled to a second power supply circuit configured to generate an RF signal.
1 . A method for plasma processing a workpiece in a plasma processing chamber, the method comprising:
placing a workpiece on an electrostatic chuck (ESC) disposed in the chamber;
coupling a first set of DC bias signals to a plurality of electrodes embedded in the ESC in a multipolar configuration, the first set of DC bias signals clamping the workpiece to the ESC;
after clamping the workpiece to the ESC, decoupling the first set of DC bias signals from the plurality of electrodes;
within a time window after decoupling the first set of DC bias signals, coupling a radio frequency (RF) signal to an RF electrode embedded in the ESC, the RF signal powering plasma in the chamber;
after powering plasma in the chamber, coupling a second set of DC bias signals to the plurality of electrodes, the second set holding the workpiece clamped to the ESC;
processing the workpiece in the chamber for a processing time duration; and
after processing the workpiece, coupling third set of DC bias signals to the plurality of electrodes, the third set releasing the workpiece from the ESC.
2 . The method of claim 1 , wherein the time window is between one millisecond and ten seconds after decoupling the first set of DC bias signals.
3 . The method of claim 1 , wherein all the DC bias signals of the second set of DC bias signals are identical.
4 . The method of claim 1 , further comprising:
prior to coupling the second set of DC bias signals to the plurality of electrodes, decoupling the RF signal from the RF electrode embedded in the ESC; and
prior to decoupling the RF signal to the RF electrode embedded in the ESC; powering the plasma with an RF signal coupled to an RF electrode outside the ESC.
5 . The method of claim 1 , further comprising forming the ESC, the forming comprising:
forming a monolithic insulating substrate by embedding a plurality of electrodes in the insulating substrate and embedding an RF electrode in the insulating substrate.
6 . The method of claim 1 , further comprising:
processing the workpiece, controlling a temperature of the workpiece with a thermal system, the temperature being in a range from −150° C. to 1000° C., the thermal system comprising:
a heater disposed in the ESC;
passageways in the ESC for flowing fluid through the ESC; and
a temperature controller controlling operation of the thermal system.
7 . A method for plasma processing a workpiece in a plasma processing chamber, the method comprising:
placing a workpiece on an electrostatic chuck (ESC) disposed in the chamber, the ESC comprising a monolithic insulating substrate with a top surface;
clamping the workpiece to the ESC, the clamping comprising coupling a first power supply circuit to a plurality of electrodes embedded in the insulating substrate in a multipolar configuration;
after clamping the workpiece to the ESC, decoupling the first power supply circuit from the plurality of electrodes; and
within a time window after decoupling the first power supply circuit, coupling a second power supply circuit to an RF electrode embedded in the ESC so as to generate an RF signal at the RF electrode, the RF signal powering plasma in the chamber, the plurality of electrodes being located between the top surface and the RF electrode.
8 . The method of claim 7 , further comprising:
positioning the plurality of electrodes in a first plane at a first distance from the top surface, and
positioning the RF electrode at a second distance from the top surface, the second distance being greater than the first distance.
9 . A method for plasma processing a workpiece in a plasma processing chamber, the method comprising:
placing a workpiece on an electrostatic chuck (ESC) disposed in the chamber, the ESC comprising a monolithic insulating substrate with a top surface;
coupling a first power supply circuit to a plurality of electrodes embedded in the insulating substrate in a multipolar configuration to receive multiple DC bias signals, the plurality of electrodes being located between the top surface and an RF electrode and supplying the multiple DC bias signals to the plurality of electrodes, a first set of the multiple DC bias signals clamping the workpiece to the ESC;
after clamping the workpiece to the ESC, decoupling the first power supply circuit from the plurality of electrodes;
within a time window after decoupling the a first power supply circuit, coupling a second power supply circuit supplying an RF signal to the RF electrode; and
supplying a second set of the multiple DC bias signals to the plurality of electrodes to release the workpiece from the ESC.
10 . The method of claim 9 , further comprising:
coupling an RF connector disposed in the ESC to the RF electrode; and
coupling a plurality of electrical connectors disposed in the ESC to the plurality of electrodes, the plurality of electrical connectors passing through insulated feedthroughs.
11 . The method of claim 9 , further comprising outputting, at the first power supply circuit,
a first set of DC bias signals for clamping the workpiece to the ESC after the workpiece is initially placed on the ESC,
a second set of DC bias signals for releasing the workpiece from the ESC, and
a third set of DC bias signals to hold the workpiece clamped to the ESC during plasma processing.
12 . The method of claim 9 , further comprising outputting, at a matching circuit in the second power supply circuit, the RF signal that is impedance matched to a load impedance at an output.
13 . The method of claim 9 , further comprising synchronously operating the first power supply circuit and the second power supply circuit.
14 . The method of claim 9 , wherein the ESC further comprises:
a heater disposed in the monolithic insulating substrate;
an electrical conductor coupled to the heater, wherein the electrical conductor passes through an insulated feedthrough in the RF electrode; and
passageways, for a cooling fluid, disposed in the monolithic insulating substrate.