Methods and apparatus for processing a substrate

A matching network configured for use with a plasma processing chamber, comprising:

• an input configured to receive one or more radio frequency (RF) signals;
• an output configured to deliver the one or more RF signals to the plasma processing chamber;
• a first variable capacitor disposed in parallel between the input and the output;
• a second variable capacitor disposed in parallel to the first variable capacitor;
• and
• a third variable capacitor connected in parallel with each of the first variable capacitor and the second variable capacitor and in series with a transistor switch,
• wherein the matching network is tunable between a first frequency for high-power operation and a second frequency for low-power operation within a pulse period of low-power operation of one or more RF bias power sources to which the matching network is configured to connect to,
• wherein the matching network is configured such that in the low-power operation the transistor switch and the third variable capacitor are in an off configuration.

A plasma processing chamber, comprising:

• a chamber body and a chamber lid;
• a RF source power connected to the chamber lid and configured to create a plasma from gases disposed in a processing region of the chamber body;
• one or more RF bias power sources configured to sustain a plasma discharge;
• and
• a matching network comprising:
• an input configured to receive one or more radio frequency (RF) signals from the one or more RF bias power sources;
• an output configured to deliver the one or more RF signals to the plasma processing chamber;
• a first variable capacitor disposed between the input and the output;
• a second variable capacitor disposed in parallel to the first variable capacitor;
• a third variable capacitor connected in parallel with each of the first variable capacitor and the second variable capacitor and in series with a transistor switch;
• and
• a controller configured to tune the matching network between a first frequency for high-power operation and a second frequency for low-power operation,
• wherein the matching network is configured such that in the low-power operation the transistor switch and the third variable capacitor are in an off configuration.