METHODS AND APPARATUS FOR SYNCHRONIZING RF PULSES IN A PLASMA PROCESSING SYSTEM

• US 20130214828A1
• Filed: 07/17/2012
• Published: 08/22/2013
• Est. Priority Date: 02/22/2012
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: John C. Valcore, Jr.
• Inventors: Lyndaker, Bradford J., Singh, Harmeet, Valcore, John C, Jr.
• Granted Patent: US 9,368,329 B2
• Time in Patent Office: Days
• US Class Current: 327/141
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32183 Matching circuits

Abstract

A synchronized pulsing arrangement for providing at least two synchronized pulsing RF signals to a plasma processing chamber of a plasma processing system is provided. The arrangement includes a first RF generator for providing a first RF signal. The first RF signal is provided to the plasma processing chamber to energize a plasma therein, the first RF signal representing a pulsing RF signal. The arrangement also includes a second RF generator for providing a second RF signal to the plasma processing chamber. The second RF generator has a sensor subsystem for detecting values of at least one parameter associated with the plasma processing chamber that reflects whether the first RF signal is pulsed high or pulsed low and a pulse controlling subsystem for pulsing the second RF signal responsive to the detecting the values of at least one parameter.

Claims

1. A synchronized pulsing arrangement for providing at least two synchronized pulsing RF signals to a plasma processing chamber of a plasma processing system, comprising:

a first RF generator for providing a first RF signal, said first RF signal provided to said plasma processing chamber to energize a plasma therein, said first RF signal representing a pulsing RF signal; and

a second RF generator for providing a second RF signal to said plasma processing chamber, said second RF generator having a sensor subsystem for detecting values of at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low and a pulse controlling subsystem for pulsing said second RF signal responsive to said detecting said values of said at least one parameter.

2. The synchronized pulsing arrangement of claim 1 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents at least one of forward RF power and reflected RF power.

3. The synchronized pulsing arrangement of claim 1 wherein said at least one parameter that reflect whether said first RF signal is pulsed high or pulsed low represents gamma, said gamma representing a numerical index indicating a degree of mismatch between reflected power and forward power of said second RF generator.

4. The synchronized pulsing arrangement of claim 1 further comprising a tool host computer, said tool host computer providing at least a trigger threshold value to enable circuitry in said sensor subsystem of said second RF generator to ascertain whether said first RF signal is pulsed high or pulsed low.

5. The synchronized pulsing arrangement of claim 4 wherein said pulse controlling subsystem is configured to generate at least a high level and a low level for said second RF signal, said high level and said low level governed by at least one value provided said tool host computer.

6. The synchronized pulsing arrangement of claim 1 wherein said second RF signal, when pulsed, comprises at least a high pulse value and a low pulse value, wherein said low pulse value is non-zero.

7. The synchronized pulsing arrangement of claim 1 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents values obtained from a VI probe.

8. The synchronized pulsing arrangement of claim 1 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an output impedance of said second RF generator.

9. The synchronized pulsing arrangement of claim 1 further comprising a match subsystem coupled to outputs of said first RF generator and said second RF generator, wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an impedance of an input of said match subsystem.

10. The synchronized pulsing arrangement of claim 1 wherein said second RF signal, when pulsed, comprises at least a predefined high pulse value and a predefined low pulse value.

11. The synchronized pulsing arrangement of claim 1 wherein said second RF signal, when pulsed, comprises at least a predefined high pulse value and a predefined low pulse value and wherein second RF signal transitions, after a predefined duration expires after being pulsed from said predefined low pulse value to said predefined high pulse value, to said predefined pulse low value.

12. The synchronized pulsing arrangement of claim 1 wherein said second RF signal, when pulsed, comprises at least a predefined high pulse value and a predefined low pulse value and wherein second RF signal transitions, after a predefined duration expires after being pulsed from said predefined high pulse value to said predefined low pulse value, to said predefined pulse high value.

13. The synchronized pulsing arrangement of claim 10 further comprising control circuitry for generating a pulse control signal to control pulsing by said first RF generator and wherein said second RF generator does not pulse responsive to a signal from said control circuitry, said second RF generator pulses at least one of high-to-low and low-to-high responsive to said detecting said values of said at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low.

14. A synchronized pulsing arrangement for providing a plurality of synchronized pulsing RF signals to a plasma processing chamber of a plasma processing system, comprising:

a first RF generator for providing a first RF signal, said first RF signal provided to said plasma processing chamber to energize a plasma therein, said first RF signal representing a pulsing RF signal;

control circuitry for generating a pulse control signal to control pulsing by said first RF generator;

a second RF generator for providing a second RF signal to said plasma processing chamber, said second RF generator having a second RF generator sensor subsystem for detecting values of at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low and a second RF generator pulse controlling subsystem for pulsing said second RF signal responsive to said detecting said values of said at least one parameter; and

a third RF generator for providing a third RF signal to said plasma processing chamber, said third RF generator having a third RF generator sensor subsystem for detecting said values of at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low and a third RF generator pulse controlling subsystem for pulsing said third RF signal responsive to said detecting said values of said at least one parameter,

wherein said second RF generator does not pulse responsive to a signal from said control circuitry, said second RF generator pulses at least one of high-to-low for said second RF signal and low-to-high for said second RF signal responsive to said detecting said values of said at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low, and

wherein said third RF generator does not pulse responsive to a signal from said control circuitry, said third RF generator pulses at least one of high-to-low for said third RF signal and low-to-high for said third RF signal responsive to said detecting said values of said at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low.

15. The synchronized pulsing arrangement of claim 14 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents at least one of forward RF power and reflected RF power.

16. The synchronized pulsing arrangement of claim 14 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents gamma, said gamma representing a numerical index indicating a degree of mismatch between reflected power and forward power of said second RF generator.

17. The synchronized pulsing arrangement of claim 14 wherein said second RF generator sensor subsystem compares said values of at least said one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low with a threshold value to ascertain when to pulse said second RF signal.

18. The synchronized pulsing arrangement of claim 14 wherein said second RF signal, when pulsed, comprises at least a high pulse value and a low pulse value, wherein said low pulse value is non-zero.

19. The synchronized pulsing arrangement of claim 14 wherein said second RF signal, when pulsed, comprises at least a predefined high pulse value and a predefined low pulse value.

20. The synchronized pulsing arrangement of claim 14 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents values obtained from a VI probe.

21. The synchronized pulsing arrangement of claim 14 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an output impedance of said second RF generator.

22. The synchronized pulsing arrangement of claim 14 further comprising a match subsystem coupled to outputs of said first RF generator and said second RF generator, wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an impedance of an input of said match subsystem.

23. The synchronized pulsing arrangement of claim 14 wherein said second RF signal, when pulsed, comprises at least a predefined high pulse value and a predefined low pulse value and wherein said second RF signal transitions, after a predefined duration expires after being pulsed from said predefined low pulse value to said predefined high pulse value, to said predefined pulse low value.

24. A method for providing a plurality of synchronized pulsing RF signals to a plasma processing chamber of a plasma processing system, comprising:

pulsing a first RF signal, using a first RF generator, said first RF signal provided to said plasma processing chamber to energize a plasma therein;

detecting values of at least one parameter associated with said plasma processing chamber that reflects whether said first RF signal is pulsed high or pulsed low; and

pulsing a second RF signal, using a second RF generator, responsive to said detecting said values of said at least one parameter.

25. The method of claim 24 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents at least one of forward RF power and reflected RF power.

26. The method of claim 24 wherein said at least one parameter that reflect whether said first RF signal is pulsed high or pulsed low represents gamma, said gamma representing a numerical index indicating a degree of mismatch between reflected power and forward power of said second RF generator.

27. The method of claim 24 further comprising receiving a trigger threshold value from a tool host computer, said trigger threshold value to enable circuitry in said sensor subsystem of said second generator to ascertain whether said first RF signal is pulsed high or pulsed low.

28. The method of claim 24 wherein said second RF signal comprises at least a high level and a low level when pulsed, said high level and said low level governed by at least one value provided said tool host computer.

29. The method of claim 24 wherein said second RF signal, when pulsed, comprises at least a high pulse value and a low pulse value, wherein said low pulse value is non-zero.

30. The method of claim 24 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents values obtained from a VI probe.

31. The method of claim 24 wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an output impedance of said second RF generator.

32. The method of claim 24 further comprising a match subsystem coupled to outputs of said first RF generator and said second RF generator, wherein said at least one parameter that reflects whether said first RF signal is pulsed high or pulsed low represents an impedance of an input of said match subsystem.

33. The method of claim 24 wherein said second RF signal, when pulsed, pulses between a predefined high pulse value and a predefined low pulse value.