Determining a value of a variable on an RF transmission model

• US 9,320,126 B2
• Filed: 12/17/2012
• Issued: 04/19/2016
• Est. Priority Date: 12/17/2012
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Valcore, John C. Jr., Lyndaker, Bradford J.
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): Alkafawi, Eman
• Application Number:
  US13/717,538
• Publication Number:
  US 20140172335A1
• Time in Patent Office: 1,219 Days
• Field of Search: 702/65, 702/64, 702/57, 702/188, 702/137, 700/121, 700/207, 315/111.21
• US Class Current: 1/1
• CPC Class Codes: G01R 19/25 using digital measurement techniques
• CPC Class Codes: G01R 29/0892 Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
• CPC Class Codes: H01J 2237/327 Arrangements for generating the plasma
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32926 Software, data control or modelling
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01P 3/00 Waveguides; Transmission lines of the waveguide type
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

Systems and methods for determining a value of a variable on a radio frequency (RF) transmission model are described. One of the methods includes identifying a complex voltage and current measured at an output of an RF generator and generating an impedance matching model based on electrical components defined in an impedance matching circuit coupled to the RF generator. The method further includes propagating the complex voltage and current through the one or more elements from the input of the impedance matching model and through one or more elements of an RF transmission model portion that is coupled to the impedance matching model to determine a complex voltage and current at the output of the RF transmission model portion.

Claims

1. A method for determining a value of a variable on a radio frequency (RF) transmission model, the method comprising:

identifying a first complex voltage and current measured at an output of an RF generator when the RF generator is coupled to a plasma chamber via an impedance matching circuit, the impedance matching circuit having an input coupled to the output of the RF generator and an output coupled to an RF transmission line;

generating an impedance matching model based on electrical components defined in the impedance matching circuit, the impedance matching model having an input and an output, the input of the impedance matching model receiving the first complex voltage and current, the impedance matching model having one or more elements;

propagating the first complex voltage and current through the one or more elements from the input of the impedance matching model to the output of the impedance matching model to determine a second complex voltage and current, wherein the second complex voltage and current is at the output of the impedance matching model;

generating an RF transmission model based on circuit components defined in the RF transmission line, the RF transmission model having an input and an output, the input of the RF transmission model coupled to the output of the impedance matching model, the RF transmission model having a portion that includes one or more elements, wherein the RF transmission model includes a model of an RF tunnel and a model of an RF strap, the RF tunnel model coupled with the RF strap model; and

propagating the second complex voltage and current through the one or more elements of the RF transmission model portion from the input of the RF transmission model to an output of the RF transmission model portion to determine a third complex voltage and current, wherein the third complex voltage and current is at the output of the RF transmission model portion.

2. The method of claim 1, wherein the first complex voltage and current received is measured at the output of the RF generator with a voltage and current probe, the voltage and current probe calibrated according to a pre-set formula.

3. The method of claim 2, wherein the pre-set formula is a standard.

4. The method of claim 3, wherein the standard is a National Institute of Standards and Technology (NIST) standard, wherein the voltage and current probe is coupled with an open circuit, a short circuit, or a load to calibrate the voltage and current probe to comply with the NIST standard.

5. The method of claim 1, wherein the third complex voltage and current includes a voltage value, a current value, and a phase between the voltage value and the current value.

6. The method of claim 1, wherein the output of the RF generator is used to transfer an RF signal to the plasma chamber via the impedance matching circuit and the RF transmission line.

7. The method of claim 1, wherein the electrical components of the impedance matching circuit include capacitors, inductors, or a combination thereof.

8. The method of claim 1, wherein the elements of the impedance matching model include capacitors, inductors, or a combination thereof.

9. The method of claim 1, wherein the electrical components of impedance matching circuit include a combination of capacitors and inductors, wherein the elements of the impedance matching model have similar characteristics as that of the electrical components of the impedance matching circuit.

10. The method of claim 1, wherein the third complex voltage and current at the output of the RF transmission model portion is for use in a system, wherein the system includes an impedance matching circuit and excludes a metrology tool at an output of the impedance matching circuit of the system, wherein the system includes an RF transmission line and excludes a metrology tool at a point on the RF transmission line of the system.

11. The method of claim 1, wherein the impedance matching model and the RF transmission model are generated within a computer.

12. The method of claim 1, wherein propagating the first complex voltage and current through the one or more elements from the input of the impedance matching model to the output of the impedance matching model to determine the second complex voltage and current comprises:

determining an intermediate complex voltage and current within an intermediate node within the impedance matching model based on the first complex voltage and current and characteristics of one or more elements of the impedance matching model coupled between the input of the impedance matching model and the intermediate node; and

determining the second complex voltage and current based on the intermediate complex voltage and current and characteristics of one or more elements of the impedance matching model coupled between the intermediate node and the output of the impedance matching model.

13. The method of claim 1, wherein the circuit components of RF transmission line include a combination of capacitors and inductors, wherein the elements of the RF transmission model have similar characteristics as that of the circuit components of the RF transmission line.

14. The method of claim 1, wherein propagating the second complex voltage and current through the one or more elements of the RF transmission model portion from the input of the RF transmission model to the output of the RF transmission model portion to determine the third complex voltage and current comprises:

determining an intermediate complex voltage and current within an intermediate node within the RF transmission model portion based on the second complex voltage and current and characteristics of one or more elements of the RF transmission model portion coupled between the input of the RF transmission model and the intermediate node; and

determining the third complex voltage and current based on the intermediate complex voltage and current and characteristics of the one or more elements of the RF transmission model portion coupled between the intermediate node and the output of the RF transmission model portion.

15. A plasma system for determining a value of a variable on a radio frequency (RF) transmission model, comprising:

an RF generator for generating an RF signal, the RF generator associated with a voltage and current probe, wherein the voltage and current probe is configured to measure a first complex voltage and current at an output of the RF generator;

an impedance matching circuit coupled to the RF generator;

a plasma chamber coupled to the impedance matching circuit via an RF transmission line, the impedance matching circuit having an input coupled to the output of the RF generator and an output coupled to the RF transmission line; and

a processor coupled to the RF generator, the processor for;

identifying the first complex voltage and current;

generating an impedance matching model based on electrical components defined in the impedance matching circuit, the impedance matching model having an input and an output, the input of the impedance matching model receiving the first complex voltage and current, the impedance matching model having one or more elements;

propagating the first complex voltage and current through the one or more elements from the input of the impedance matching model to the output of the impedance matching model to determine a second complex voltage and current, wherein the second complex voltage and current is at the output of the impedance matching model;

generating an RF transmission model based on electrical components defined in the RF transmission line, the RF transmission model having an input and an output, the input of the RF transmission model coupled to the output of the impedance matching model, the RF transmission model having a portion that includes one or more elements, wherein the RF transmission model includes a model of an RF tunnel and a model of an RF strap, the RF tunnel model coupled with the RF strap model;

propagating the second complex voltage and current through the one or more elements of the RF transmission model portion from the input of the RF transmission model to an output of the RF transmission model portion to determine a third complex voltage and current, wherein the third complex voltage and current is at the output of the RF transmission model portion; and

providing the third complex voltage and current for storage to a storage hardware unit.

16. The system of claim 15, wherein the voltage and current probe is calibrated to comply with a pre-set formula.

17. The system of claim 16, wherein the pre-set formula is a standard, wherein the standard is a National Institute of Standards and Technology (NIST) standard, wherein the voltage and current probe is coupled with an open circuit, a short circuit, or a load to calibrate the voltage and current probe to comply with the NIST standard.

18. A computer system for determining a value of a variable on a radio frequency (RF) transmission model, the computer system comprising:

a processor configured to;

identify a first complex voltage and current measured at an output of an RF generator when the RF generator is coupled to a plasma chamber via an impedance matching circuit, the impedance matching circuit having an input coupled to the output of the RF generator and an output coupled to an RF transmission line;

generate an impedance matching model based on electrical components defined in the impedance matching circuit, the impedance matching model having an input and an output, the input of the impedance matching model receiving the first complex voltage and current, the impedance matching model having one or more elements;

propagate the first complex voltage and current through the one or more elements from the input of the impedance matching model to the output of the impedance matching model to determine a second complex voltage and current, wherein the second complex voltage and current is at the output of the impedance matching model;

generate an RF transmission model based on electrical components defined in the RF transmission line, the RF transmission model having an input and an output, the input of the RF transmission model coupled to the output of the impedance matching model, the RF transmission model having a portion that includes one or more elements, wherein the RF transmission model includes a model of an RF tunnel and a model of an RF strap, the RF tunnel model coupled with the RF strap model; and

propagate the second complex voltage and current through the one or more elements of the RF transmission model portion from the input of the RF transmission model to an output of the RF transmission model portion to determine a third complex voltage and current, wherein the third complex voltage and current is at the output of the RF transmission model portion; and

a memory device coupled to the processor, the memory device configured to store the third complex voltage and current.

19. The computer system of claim 18, wherein the first complex voltage and current received is measured at the output of the RF generator with a voltage and current probe, the voltage and current probe calibrated according to a pre-set formula.

20. The computer system of claim 19, wherein the voltage and current probe is decoupled from a digital signal processor of the RF generator.