# US 2014/0197731 A1 · Tuning A Parameter Associated With Plasma Impedance

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0197731 A1
- Document ID: US20140197731A1
- Status: Published application
- Kind: A1
- Application number: 13/740,047
- Filed: 2013-01-11
- Published: 2014-07-17
- Earliest claimed: 2013-01-11
- Assignees: Lam Research Corporation
- Inventors: John C. Valcore, JR.; Bradford J. Lyndaker
- Web page: https://patentgrep.com/patent/US20140197731A1

## CPC

- H05H 1/46: using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence)
- H01J 37/321: {the radio frequency energy being inductively coupled to the plasma}
- H01J 37/32183: {Matching circuits}
- H01J 37/3244: {Gas supply means}
- H01J 37/32935: {Monitoring and controlling tubes by information coming from the object and/or discharge}
- H01J 37/3299: {Feedback systems}
- H01J 37/32082: {Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence)}
- H05H 1/466: {using capacitive coupling means, e.g. electrodes}
- H05H 2242/26: Matching networks
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Systems and methods for tuning a parameter associated with plasma impedance are described. One of the methods includes receiving information to determine a variable. The information is measured at a transmission line and is measured when the parameter has a first value. The transmission line is used to provide power to a plasma chamber. The method further includes determining whether the variable is at a local minima and providing the first value to tune the impedance matching circuit upon determining that the variable is at the local minima. The method includes changing the first value to a second value of the parameter upon determining that the variable is not at the local minima and determining whether the variable is at a local minima when the parameter has the second value.

## Claims

### Claim 1

A method for tuning a parameter associated with plasma impedance, comprising:
receiving information to determine a variable, the information measured at a transmission line, the information measured when the parameter has a first value, the transmission line used to provide power to a plasma chamber via an impedance matching circuit;
determining whether the variable is at a local minima;
providing the first value to tune the impedance matching circuit upon determining that the variable is at the local minima;
changing the first value to a second value of the parameter upon determining that the variable is not at the local minima; and
determining whether the variable is at a local minima when the parameter has the second value,
wherein the method is executed by a processor.

### Claim 2 (depends on 1)

The method of claim 1, wherein said determining whether the variable is at a local minima when the parameter has a first value comprises:
determining whether the variable exceeds a threshold when the parameter has the first value; or
determining whether the variable is stable when the parameter has the first value; or
a combination thereof.

### Claim 3 (depends on 2)

The method of claim 2, wherein the variable is stable when the variable lacks oscillation.

### Claim 4 (depends on 2)

The method of claim 2, wherein the variable is unstable when the variable oscillates between a minimum value and a maximum value, and a range between the minimum value and the maximum value exceeds a predetermined range.

### Claim 5 (depends on 1)

The method of claim 1, wherein the method is executed during processing of a substrate, wherein the method is performed without using a learned value of the parameter.

### Claim 6 (depends on 5)

The method of claim 5, wherein the substrate is implemented within an electronic device.

### Claim 7 (depends on 1)

The method of claim 1, wherein the parameter includes frequency, capacitance, inductance, or a combination thereof.

### Claim 8 (depends on 1)

The method of claim 1, wherein the information includes voltage, current, power, or a combination thereof, wherein the variable includes gamma, reflected power, complex voltage reflection coefficient, plasma impedance, or a combination thereof.

### Claim 9 (depends on 1)

The method of claim 1, wherein the local minima is other than an absolute minima, wherein the absolute minima includes a reflected power of zero watts.

### Claim 10 (depends on 1)

The method of claim 1, wherein the processor is within a host system, the host system coupled to a radio frequency (RF) generator, the RF generator coupled to the plasma chamber via the impedance matching circuit.

### Claim 11

A method for tuning a parameter associated with plasma impedance, comprising:
receiving information to determine a variable, the information measured at a transmission line, the information measured when the parameter has a first value, the transmission line used to provide power to a plasma chamber via an impedance matching circuit;
determining whether the variable is at a local minima;
providing the first value to generate a radio frequency (RF) signal upon determining that the variable is at the local minima, the RF signal corresponding to the first value, the RF signal to be sent to the plasma chamber;
changing the first value to a second value of the parameter upon determining that the variable is not at the local minima; and
determining whether the variable is at a local minima when the parameter has the second value,
wherein the method is executed by a processor.

### Claim 12 (depends on 11)

The method of claim 11, wherein said determining whether the variable is at a local minima when the parameter has a first value comprises:
determining whether the variable exceeds a threshold when the parameter has the first value; or
determining whether the variable is stable when the parameter has the first value; or
a combination thereof.

### Claim 13 (depends on 11)

The method of claim 11, wherein the information includes voltage, current, power, or a combination thereof, wherein the variable includes gamma, reflected power, complex voltage reflection coefficient, plasma impedance, or a combination thereof.

### Claim 14

A method for tuning a parameter associated with plasma impedance, comprising:
receiving information to determine a variable, the information measured at a transmission line, the information measured when the parameter has a first value, the transmission line used to provide power to a plasma chamber via an impedance matching circuit;
determining whether the variable is at a local minima when the parameter has the first value;
determining whether the first value of the parameter is within a limit of a learned value upon determining that the variable is at the local minima, the learned value determined during a learning routine;
providing the learned value to generate a radio frequency (RF) signal or to tune the impedance matching circuit upon determining that the first value of the parameter is within the limit; and
changing the first value to a second value of the parameter upon determining that the parameter has the first value that is outside the limit,
wherein the method is executed by a processor.

### Claim 15 (depends on 14)

The method of claim 14, wherein said determining whether the variable is at a local minima when the parameter has a first value comprises:
determining whether the variable exceeds a threshold when the parameter has the first value; and
determining whether the variable is stable when the parameter has the first value.

### Claim 16 (depends on 15)

The method of claim 15, wherein the variable is unstable when the variable oscillates between a minimum value and a maximum value, and a range between the minimum value and the maximum value exceeds a predetermined range.

### Claim 17 (depends on 16)

The method of claim 16, wherein the variable is stable when the variable lacks oscillation.

### Claim 18 (depends on 15)

The method of claim 15, wherein the method is executed during processing of a substrate.

### Claim 19 (depends on 18)

The method of claim 18, wherein the substrate is implemented within an electronic device.

### Claim 20

A method for tuning a parameter associated with plasma impedance, comprising:
receiving information to determine a variable, the information measured at a transmission line, the information measured when the parameter has a first value, the transmission line used to provide power to a plasma chamber via an impedance matching circuit;
determining a local minima of the variable, the local minima achieved when the parameter has the first value;
tuning the parameter by changing the first value to one or more other values of the parameter;
determining a number of events for which the variable is unstable when the parameter has the one or more other values;
determining whether the number of events exceeds a boundary;
reversing a direction of tuning the parameter upon determining that the number of events exceeds the boundary; and
discontinuing further tuning of the parameter upon determining that the number of events does not exceed the boundary,
wherein the method is executed by a processor.

### Claim 21 (depends on 20)

The method of claim 20, wherein said determining the local minima of the variable comprises:
determining that the variable does not exceed a threshold when the parameter has the first value; and
determining that the variable is stable when the parameter has the first value.

### Claim 22 (depends on 20)

The method of claim 20, wherein said reversing the direction of tuning the parameter includes increasing a value of the parameter or decreasing a value of the parameter.

### Claim 23 (depends on 20)

The method of claim 20, wherein the method is executed during processing of a substrate, wherein the method is performed without knowledge of a learned value of the parameter, wherein the local minima is other than an absolute minima, wherein the processor is within a host system, the host system coupled to a radio frequency (RF) generator, the RF generator coupled to the plasma chamber via the impedance matching circuit.

### Claim 24 (depends on 20)

The method of claim 20, wherein the method is executed during processing of a substrate, wherein the substrate is implemented within an electronic device.