SYSTEM, METHOD AND APPARATUS FOR USING OPTICAL DATA TO MONITOR RF GENERATOR OPERATIONS

• US 20170200592A1
• Filed: 03/28/2017
• Published: 07/13/2017
• Est. Priority Date: 08/29/2014
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: San, Tony, Lee, Seonkyung, Valcore, JR., John C.
• Granted Patent: US 10,325,760 B2
• Time in Patent Office: Days
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

A system and method monitoring a plasma with an optical sensor to determine the operations of a pulsed RF signal for plasma processing including a plasma chamber with an optical sensor directed toward a plasma region. An RF generator coupled to the plasma chamber through a match circuit. An RF timing system coupled to the RF generator. A system controller is coupled to the plasma chamber, the RF generator, the optical sensor, the RF timing system and the match circuit. The system controller includes a central processing unit, a memory system, a set of RF generator settings and an optical pulsed plasma analyzer coupled to the optical sensor and being capable to determine a timing of a change in state of an optical emission received in the optical sensor and/or a set of amplitude statistics corresponding to an amplitude of the optical emission received in the optical sensor.

Claims

1. A method comprising:

receiving a signal from an optical sensor facing a plasma chamber when an RF signal is supplied to the plasma chamber, wherein the RF signal transitions between a first state and a second state;

dividing the RF signal into a plurality of subdivisions;

dividing the optical sensor signal into a plurality of subdivisions;

determining an amplitude statistic for each of the subdivisions of the optical sensor signal; and

controlling a parameter of the RF signal for one of the subdivisions of the RF signal based on the amplitude statistic for a corresponding one of the subdivisions of the optical sensor signal.

2. The method of claim 1, wherein the RF signal is divided into the same number of subdivisions for each of the first state and the second state of the RF signal.

3. The method of claim 2, wherein the optical sensor signal is divided into a first number of subdivisions during a time period in which the RF signal is in the first state, wherein the optical sensor signal is divided into a second number of subdivisions during a time period in which the RF signal is in the second state, wherein the first number is the same as the second number.

4. The method of claim 3, wherein the amplitude statistic is a maximum of amplitude values of the optical sensor signal, or a minimum of the amplitude values of the optical sensor signal, or a mean of the amplitude values of the optical sensor signal.

5. The method of claim 1, wherein the parameter of the RF signal is a frequency and power of the RF signal.

6. The method of claim 1, wherein the one of the subdivisions of the RF signal has the same time period as that the corresponding one of the subdivisions of the optical sensor signal, wherein the time period starts at a time and ends at a time.

7. The method claim 1, further comprising controlling other parameters of the plasma chamber for the one of the subdivisions of the RF signal based on the amplitude statistic for the corresponding one of the subdivisions of the optical sensor signal, wherein the other parameters include a pressure, a temperature of the plasma chamber, and a distance between an upper electrode of the plasma chamber and a lower electrode of the plasma chamber.

8. A plasma processing system comprising:

a plasma chamber having an optical sensor directed toward a plasma region in the plasma chamber;

an RF generator coupled to the plasma chamber through a match circuit, wherein the RF generator is configured to generate an RF signal and provide the RF signal via the match circuit to the plasma chamber, wherein the RF signal transitions between a first state and a second state;

a system controller coupled to the plasma chamber and the RF generator, the system controller configured to;

receive a signal from the optical sensor when the RF signal is supplied to the plasma chamber;

divide the RF signal into a plurality of subdivisions;

divide the optical sensor signal into a plurality of subdivisions;

determine an amplitude statistic for each of the subdivisions of the optical sensor signal; and

control a parameter of the RF signal for one of the subdivisions of the RF signal based on the amplitude statistic for a corresponding one of the subdivisions of the optical sensor signal.

9. The plasma system of claim 8, wherein the RF signal is divided into the same number of subdivisions for each of the first state and the second state of the RF signal.

10. The plasma system of claim 9, wherein the optical sensor signal is divided into a first number of subdivisions during a time period in which the RF signal is in the first state, wherein the optical sensor signal is divided into a second number of subdivisions during a time period in which the RF signal is in the second state, wherein the first number is the same as the second number.

11. The plasma system of claim 10, wherein the amplitude statistic is a maximum of amplitude values of the optical sensor signal, or a minimum of the amplitude values of the optical sensor signal, or a mean of the amplitude values of the optical sensor signal.

12. The plasma system of claim 8, wherein the parameter of the RF signal is a frequency and power of the RF signal.

13. The plasma system of claim 8, wherein the one of the subdivisions of the RF signal has the same time period as that the corresponding one of the subdivisions of the optical sensor signal, wherein the time period starts at a time and ends at a time.

14. The plasma system of claim 8, wherein the system controller is configured to control other parameters of the plasma chamber for one of the subdivisions of the RF signal based on the amplitude statistic for a corresponding one of the subdivisions of the optical sensor signal, wherein the other parameters include a pressure, a temperature of the plasma chamber, and a distance between an upper electrode of the plasma chamber and a lower electrode of the plasma chamber.

15. A non-transitory computer-readable storage medium having stored thereon a computer program, the computer program comprising instructions for causing a processor to perform a plurality of operations of:

receiving a signal from an optical sensor facing a plasma chamber when an RF signal is supplied to the plasma chamber, wherein the RF signal transitions between a first state and a second state;

dividing the RF signal into a plurality of subdivisions;

dividing the optical sensor signal into a plurality of subdivisions;

determining an amplitude statistic for each of the subdivisions of the optical sensor signal; and

controlling a parameter of the RF signal for one of the subdivisions of the RF signal based on the amplitude statistic for a corresponding one of the subdivisions of the optical sensor signal.

16. The non-transitory computer-readable storage medium of claim 15, wherein the RF signal is divided into the same number of subdivisions for each of the first state and the second state of the RF signal.

19. The non-transitory computer-readable storage medium of claim 15, wherein the parameter of the RF signal is a frequency and power of the RF signal.

20. The non-transitory computer-readable storage medium of claim 15, wherein the one of the subdivisions of the RF signal has the same time period as that the corresponding one of the subdivisions of the optical sensor signal, wherein the time period starts at a time and ends at a time.

17. The non-transitory computer-readable storage medium of claim 17, wherein the optical sensor signal is divided into a first number of subdivisions during a time period in which the RF signal is in the first state, wherein the optical sensor signal is divided into a second number of subdivisions during a time period in which the RF signal is in the second state, wherein the first number is the same as the second number.

18. The non-transitory computer-readable storage medium of claim 17, wherein the amplitude statistic is a maximum of amplitude values of the optical sensor signal, or a minimum of the amplitude values of the optical sensor signal, or a mean of the amplitude values of the optical sensor signal.