RF impedance matching network

A method of matching an impedance, the method comprising:

• determining a variable load impedance of a load, with an impedance matching network coupled between the load and an RF source, wherein the RF source has a fixed RF source impedance, and the impedance matching network comprises:
• an RF input configured to couple to the RF source;
• an RF output configured to couple to the load;
• a transformation circuit coupled to the RF input and configured to provide a transformed impedance that is less than the RF fixed source impedance, the transformation circuit comprising:
• a transformation capacitor in series with the RF input;
• and
• a transformation inductor in parallel to the RF input and coupled to a ground;
• a series inductor in series with the RF input and coupled between the transformation capacitor and the RF output;
• a first shunt circuit in parallel to the RF input, the first shunt circuit comprising:
• a first shunt variable capacitance component comprising (a) a plurality of first shunt capacitors coupled in parallel, and (b) a plurality of first shunt switches coupled to the plurality of first shunt capacitors and configured to connect and disconnect each of the plurality of first shunt capacitors to a first virtual ground;
• a first shunt padding capacitor coupled in parallel to at least one of the plurality of first shunt capacitors, the first shunt padding capacitor coupled to the first virtual ground;
• a first shunt ground capacitor coupled between the first virtual ground and the ground;
• and
• a first shunt resistor coupled between the first virtual ground and the ground;
• a second shunt circuit in parallel to the RF output, the second shunt circuit comprising:
• a second shunt variable capacitance component comprising (a) a plurality of second shunt capacitors coupled in parallel, and (b) a plurality of second shunt switches coupled to the plurality of second shunt capacitors and configured to connect and disconnect each of the plurality of second shunt capacitors to a second virtual ground;
• a second shunt padding capacitor coupled in parallel to at least one of the plurality of second shunt capacitors, the second shunt padding capacitor coupled to the second virtual ground;
• a second shunt ground capacitor coupled between the second virtual ground and the ground;
• and
• a second shunt resistor coupled between the second virtual ground and the ground;
• determining a first shunt capacitance value for the first shunt variable capacitance component and a second shunt capacitance value for the second shunt variable capacitance component for creating an impedance match at an RF input of the impedance matching network;
• and
• generating a control signal to cause the first shunt variable capacitance component to provide the first shunt capacitance value, or to cause the second shunt variable capacitance component to provide the second shunt capacitance value.

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:
• determining a variable load impedance of the plasma chamber, with an impedance matching network coupled between the load and the RF source, wherein the RF source has a fixed RF source impedance, and the impedance matching network comprises:
• an RF input configured to couple to the RF source;
• an RF output configured to couple to the load;
• a transformation circuit coupled to the RF input and configured to provide a transformed impedance that is less than the RF fixed source impedance, the transformation circuit comprising:
• a transformation capacitor in series with the RF input;
• and
• a transformation inductor in parallel to the RF input and coupled to a ground;
• a series inductor in series with the RF input and coupled between the transformation capacitor and the RF output;
• a first shunt circuit in parallel to the RF input, the first shunt circuit comprising:
• a first shunt variable capacitance component comprising (a) a plurality of first shunt capacitors coupled in parallel, and (b) a plurality of first shunt switches coupled to the plurality of first shunt capacitors and configured to connect and disconnect each of the plurality of first shunt capacitors to a first virtual ground;
• a first shunt padding capacitor coupled in parallel to at least one of the plurality of first shunt capacitors, the first shunt padding capacitor coupled to the first virtual ground;
• a first shunt ground capacitor coupled between the first virtual ground and the ground;
• and
• a first shunt resistor coupled between the first virtual ground and the ground;
• a second shunt circuit in parallel to the RF output, the second shunt circuit comprising:
• a second shunt variable capacitance component comprising (a) a plurality of second shunt capacitors coupled in parallel, and (b) a plurality of second shunt switches coupled to the plurality of second shunt capacitors and configured to connect and disconnect each of the plurality of second shunt capacitors to a second virtual ground;
• a second shunt padding capacitor coupled in parallel to at least one of the plurality of second shunt capacitors, the second shunt padding capacitor coupled to the second virtual ground;
• a second shunt ground capacitor coupled between the second virtual ground and the ground;
• and
• a second shunt resistor coupled between the second virtual ground and the ground;
• determining a first shunt capacitance value for the first shunt variable capacitance component and a second shunt capacitance value for the second shunt variable capacitance component for creating an impedance match at an RF input of the impedance matching network;
• and
• generating a control signal to cause the first shunt variable capacitance component to provide the first shunt capacitance value, or to cause the second shunt variable capacitance component to provide the second shunt capacitance value.