RF impedance matching network

Patent metadata

Field	Value
Publication number	US-10026594-B2
Application number	US-201615291260-A
Country	US
Kind code	B2
Filing date	Oct 12, 2016
Priority date	Jan 10, 2014
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

In one embodiment, an RF impedance matching network includes an RF input configured to operably couple to an RF source; an RF output configured to operably couple to a plasma chamber; a first electronically variable capacitor having a first variable capacitance; a second electronically variable capacitor having a second variable capacitance; and a control circuit operably coupled to the first and second electronically variable capacitors. The control circuit is configured to determine the variable impedance of the plasma chamber, determine a first capacitance value for the first variable capacitance and a second capacitance value for the second variable capacitance, and generate a control signal to alter the first and/or second variable capacitance. An elapsed time between determining the variable impedance of the plasma chamber to when RF power reflected back to the RF source decreases is less than about 150 μsec.

First claim

What is claimed is:

1. A radio frequency (RF) impedance matching network comprising:
an RF input configured to operably couple to an RF source;
an RF output configured to operably couple to a plasma chamber having a variable impedance;
a first electronically variable capacitor having a first variable capacitance;
a second electronically variable capacitor having a second variable capacitance; and
a control circuit operably coupled to the first electronically variable capacitor and to the second electronically variable capacitor to control the first variable capacitance and the second variable capacitance, wherein the control circuit is configured to:
determine the variable impedance of the plasma chamber;
determine a first capacitance value for the first variable capacitance and a second capacitance value for the second variable capacitance; and
generate a control signal to alter at least one of the first variable capacitance and the second variable capacitance to the first capacitance value and the second capacitance value, respectively;
wherein an elapsed time between determining the variable impedance of the plasma chamber to when RF power reflected back to the RF source decreases is less than about 150 μsec.

2. The RF impedance matching network of claim 1 wherein the impedance match is created in about 500 μsec or less.

3. The RF impedance matching network of claim 1 further comprising:
a first driver circuit operably coupled between the control circuit and the first electronically variable capacitor, the first driver circuit being configured to alter the first variable capacitance based upon the control signal received from the control circuit;
a second driver circuit operably coupled between the control circuit and the second electronically variable capacitor, the second driver circuit being configured to alter the second variable capacitance based upon the control signal received from the control circuit;
a first RF filter operably coupled between the first electronically variable capacitor and the first driver circuit; and
a second RF filter operably coupled between the second electronically variable capacitor and the second driver circuit.

4. The RF impedance matching network of claim 1 wherein the first electronically variable capacitor is operably coupled in series between the RF input and the RF output.

5. The RF impedance matching network of claim 4 wherein the first electronically variable capacitor and the second electronically variable capacitor are positioned to form a T type matching network, the second electronically variable capacitor being operably coupled in series between the RF input and the RF output.

6. The RF impedance matching network of claim 1 wherein the second electronically variable capacitor is operably coupled in parallel between a ground and one of the RF input and the RF output.

7. The RF impedance matching network of claim 6 wherein the first electronically variable capacitor and the second electronically variable capacitor are positioned to form a pi (Π) type matching network, the first electronically variable capacitor being operably coupled between a ground and one of the RF input and the RF output.

8. The RF impedance matching network of claim 1 wherein the determination of the first capacitance value for the first variable capacitance and the second capacitance value for the second variable capacitance is based on the determined variable impedance of the plasma chamber.

9. A method of matching an impedance, the method comprising:
determining, by an impedance matching network, a variable impedance of a plasma chamber, the impedance matching network comprising an RF input configured to operably couple to an RF source, 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 variable capacitance value and a second variable capacitance value for, respectively, the first electronically variable capacitor and the second electronically variable capacitor, for creating an impedance match at the RF input of the impedance matching network; and
altering at least one of the first variable capacitance and the second variable capacitance to the first capacitance value and the second capacitance value, respectively, wherein an elapsed time between determining the variable impedance of the plasma chamber to when RF power reflected back to the RF source decreases is less than about 150 μsec.

10. The method of claim 9 wherein the steps of determining the first variable capacitance value and the second variable capacitance value and altering the at least one of the first variable capacitance and the second variable capacitance are repeated to create the impedance match.

11. The method of claim 10 wherein the impedance match is created in an elapsed time of about 500 μsec or less.

12. The method of claim 9 wherein the altering of the at least one of the first variable capacitance and the second variable capacitance comprises sending a control signal to at least one of a first driver circuit and a second driver circuit to control the first variable capacitance and the second variable capacitance, respectively, the first driver circuit operably coupled to the first electronically variable capacitor, and the second driver circuit operably coupled to the second electronically variable capacitor.

13. The method of claim 9 wherein the first electronically variable capacitor is operably coupled in series between the RF input and the RF output.

14. The method of claim 13 wherein the first electronically variable capacitor and the second electronically variable capacitor are positioned such that the impedance matching network is a T type matching network, the second electronically variable capacitor being operably coupled in series between the RF input and the RF output.

15. The method of claim 9 wherein the second electronically variable capacitor is operably coupled in parallel between a ground and one of the RF input and the RF output.

16. The method of claim 15 wherein the first electronically variable capacitor and the second electronically variable capacitor are positioned such that the impedance matching network is a pi (Π) type matching network, the first electronically variable capacitor being operably coupled between a ground and one of the RF input and the RF output.

17. The method of claim 9 wherein each of the first electronically variable capacitor and the second electronically variable capacitor comprises a plurality of discrete capacitors, each discrete capacitor having a corresponding switch to activate or deactivate the discrete capacitor;
wherein the first variable capacitance is altered to the first capacitance value by activating or deactivating at least one of the discrete capacitors of the first electronically variable capacitor; and
wherein the second variable capacitance is altered to the second capacitance value by activating or deactivating at least one of the discrete capacitors of the second electronically variable capacitor.

18. The method of claim 9 wherein the determination of the first capacitance value for the first variable capacitance and the second capacitance value for the second variable capacitance is based on the determined variable impedance of the plasma chamber.

19. A method of manufacturing a semiconductor comprising:
placing a substrate in a plasma chamber conf

Assignees

• Reno Tech Inc

Inventors

• Bhutta Imran Ahmed

Classifications

• H10P50/287

  by chemical means · CPC title

• H10P50/283

  by chemical means · CPC title

• H10P50/267

  using plasmas · CPC title

• H10P50/242

  of Group IV materials · CPC title

• H10P14/6336

  in the presence of a plasma [PECVD] · CPC title