Transformer coupled capacitive tuning circuit with fast impedance switching for plasma etch chambers

A transformer coupled capacitive tuning (TCCT) circuit for an inductively coupled plasma (ICP) chamber, comprising:

• a matching circuit including a first switched capacitor circuit and a first inductor,
• wherein the first switched capacitor circuit includes:
• a first terminal;
• a second terminal;
• a first capacitor connected to at least one of the first terminal and the second terminal;
• a second capacitor connected to at least one of the first terminal and the second terminal;
• and
• a first switch in communication with at least one of the first capacitor and the second capacitor to vary a capacitance value between the first terminal and the second terminal;
• and
• a power splitter in communication with the matching circuit and an inductive coil of the ICP chamber, wherein the power splitter includes:
• a third capacitor having a first terminal connected to an output of the matching circuit;
• a fourth capacitor having a first terminal connected to a second terminal of the third capacitor and a second terminal in communication with a first coil;
• a fifth capacitor having a first terminal connected to the output of the matching circuit;
• a second inductor including a first terminal connected to a second terminal of the fifth capacitor;
• a sixth capacitor having a first terminal connected to a second terminal of the second inductor and a second terminal connected to a second coil;
• and
• a seventh capacitor connected to the first coil.

A substrate processing system comprising:

• a transformer coupled capacitive tuning (TCCT) circuit for an inductively coupled plasma (ICP) chamber, comprising:
• a matching circuit including a first switched capacitor circuit and a first inductor,
• wherein the first switched capacitor circuit includes:
• a first terminal;
• a second terminal;
• a first capacitor connected to at least one of the first terminal and the second terminal;
• a second capacitor connected to at least one of the first terminal and the second terminal;
• and
• a first switch in communication with at least one of the first capacitor and the second capacitor to vary a capacitance value between the first terminal and the second terminal;
• and
• a power splitter in communication with the matching circuit and an inductive coil of the ICP chamber;
• and
• the substrate processing system further comprising:
• an RF generator to generate an RF input signal to the TCCT circuit;
• an RF bias generator to bias a substrate support in the ICP chamber;
• and
• a controller configured to:
• during a first half cycle, supply a first capacitance value from the first switched capacitor circuit, and supply the RF input signal at a first amplitude and the RF bias at a second amplitude;
• and
• during a second half cycle, supply a second capacitance value from the first switched capacitor circuit, and supply the RF input signal at a third amplitude and the RF bias at a fourth amplitude,
• wherein the first capacitance value is different than the second capacitance value, and wherein the first amplitude is different than the third amplitude and the second amplitude is different than the fourth amplitude.