RF impedance matching circuit and systems and methods incorporating same

A method of matching an impedance, the method comprising:

• coupling an impedance matching circuit between an RF source and a plasma chamber, the impedance matching circuit comprising:
• an RF input configured to operably couple to the RF source providing an RF signal having a frequency;
• an RF output configured to operably couple to the plasma chamber;
• a first electronically variable capacitor having a first variable capacitance;
• and
• a second electronically variable capacitor having a second variable capacitance;
• determining a first parameter related to the plasma chamber;
• determining, based on the first parameter, a first variable capacitance value for the first electronically variable capacitor and a second variable capacitance value for the second electronically variable capacitor, for creating an impedance match at the RF input of the impedance matching circuit;
• and
• altering the first variable capacitance and the second variable capacitance to the first capacitance value and the second capacitance value, respectively, wherein the alteration of the first variable capacitance and the second variable capacitance causes RF power reflected back to the RF source to decrease while the frequency of the RF source is not altered.

A method of manufacturing a semiconductor comprising:

• placing a substrate in a plasma chamber configured to deposit a material layer onto the substrate or etch a material layer from the substrate;
• and
• energizing plasma within the plasma chamber by coupling RF power from an RF source into the plasma chamber to perform a deposition or etching, and while energizing the plasma:
• coupling an impedance matching circuit between the RF source and the plasma chamber, the impedance matching circuit comprising:
• an RF input configured to operably couple to the RF source, the RF source providing an RF signal having a frequency;
• an RF output configured to operably couple to the plasma chamber;
• a first electronically variable capacitor having a first variable capacitance;
• and
• a second electronically variable capacitor having a second variable capacitance;
• determining a first parameter related to the plasma chamber;
• determining, based on the first parameter, a first variable capacitance value for the first electronically variable capacitor and a second variable capacitance value for the second electronically variable capacitor, for creating an impedance match at the RF input of the impedance matching circuit;
• and
• altering the first variable capacitance and the second variable capacitance to the first capacitance value and the second capacitance value, respectively, wherein the alteration of the first variable capacitance and the second variable capacitance causes RF power reflected back to the RF source to decrease while the frequency of the RF source is not altered.

A semiconductor processing tool comprising:

• a plasma chamber configured to deposit a material onto a substrate or etch a material from the substrate;
• and
• an impedance matching circuit operably coupled to the plasma chamber, the matching circuit comprising:
• an RF input operably coupled to an RF source providing an RF signal having a frequency;
• an RF output operably coupled to the plasma chamber;
• a first electronically variable capacitor having a first variable capacitance;
• and
• a second electronically variable capacitor having a second variable capacitance;
• and
• a control circuit operably coupled to the first and second electronically variable capacitors to control the first variable capacitance and the second variable capacitance, wherein the control circuit is configured to:
• determine a first parameter related to the plasma chamber;
• determine, based on the first parameter, a first capacitance value for the first electronically variable capacitor and a second capacitance value for the second electronically variable capacitor;
• and
• generate a control signal to alter the first variable capacitance and the second variable capacitance to the first capacitance value and the second capacitance value, respectively;
• wherein the alteration of the first variable capacitance and the second variable capacitance causes RF power reflected back to the RF source to decrease while the frequency of the RF source is not altered.