System and method for non-invasive sensing of radio-frequency current spectra flowing in a plasma processing chamber
A system for non-invasive sensing of radio-frequency current spectra. In one example, the system comprises a plasma processing chamber, a plasma generator, and a shunt connector having a resistor therein. In one example, the shunt connector is attached across an opening in a ground-return path between the chamber and the generator.
1 . A system for non-Invasive sensing of radio-frequency current spectra comprising:
a plasma processing chamber;
a plasma generator;
a shunt connector having a resistor therein, the shunt connector bridging an opening in a ground-return path between the chamber and the generator; and
an amplifier configured to detect the voltage drop generated by the resistor and output an RF signal.
2 . The system of claim 1 , wherein the system is configured to detect current flowing through the ground-return path.
3 . The system of claim 2 , wherein the system is configured such that current flowing through the ground-return path generates a voltage in the resistor.
4 . The system of claim 1 , wherein the shunt connector is configured to be attached across a viewport of the chamber.
5 . The system of claim 1 , further comprising a digitisation circuit configured to take the RF signal from the amplifier and convert it to a digital signal for processing and analysis.
6 . The system of claim 5 , wherein the RF signal is an alternating current signal in the RF band.
7 . The system of claim 1 wherein the RF signal is an alternating current signal in the RF band.
8 . The system of claim 1 , further comprising a housing in which the resistor and amplifier are enclosed.
9 . The system of claim 1 , wherein the system is configured such that the shunt connector and the resistor create a path for current to flow as part of the ground-return path.
10 . The system of claim 9 , wherein the path created by the shunt connector and the resistor is orientated in the same direction as current flow in the ground-return path.
11 . The system of claim 1 , wherein the shunt connector comprises at least one of a ground shunt strap, cable, bar and rod.
12 . A method for non-Invasive sensing of radio-frequency current spectra flowing in a plasma processing chamber comprising:
providing a shunt connector having a resistor therein; and
attaching the shunt connector across an opening in a ground-return path between the chamber and a plasma generator; and
coupling an amplifier to the shunt connector to detect the voltage drop generated by the resistor and output an RF signal.
13 . The method of claim 12 , further comprising detecting current flowing through the ground-return path.
14 . The method of claim 13 , wherein current flowing through the ground return path generates a voltage in the resistor.
15 . The method of claim 12 , further comprising attaching the shunt connector across a viewport of the chamber.
16 . The method of claim 13 , further comprising attaching the shunt connector across a viewport of the chamber.