Methods and apparatus for synchronizing rf pulses in a plasma processing system

Patent metadata

Field	Value
Publication number	US-2016268100-A1
Application number	US-201615162528-A
Country	US
Kind code	A1
Filing date	May 23, 2016
Priority date	Feb 22, 2012
Publication date	Sep 15, 2016
Grant date	—

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 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.

First claim

What is claimed is:

1 . A method comprising:
generating a first radio frequency (RF) signal, wherein the first RF signal is a pulse signal; sending the first RF signal to an impedance match network, wherein the impedance match network is coupled to a plasma chamber; generating a second RF signal; sending the second RF signal to the impedance match network; sensing a parameter indicating a change in an impedance of plasma within the plasma chamber, wherein the change in the impedance occurs when a state of the first RF signal changes from one state to another; and pulsing the second RF signal from one state to another upon sensing the parameter indicating the change in the impedance.

2 . The method of claim 1 , wherein the parameter is sensed at an output of an RF generator that generates the second RF signal.

3 . The method of claim 1 , wherein the first RF signal is a low-frequency RF signal and the second RF signal is a high-frequency RF signal, wherein the high-frequency is greater than the low-frequency, wherein the parameter is associated with forward power and reflected power.

4 . The method of claim 1 , wherein the one state of the first RF signal is an on state and the other state of the first RF signal is an off state, wherein the one state of the second RF signal is an on state and the other state of the second RF signal is an off state, wherein the change in the plasma impedance occurs as a consequence of a transition of the first RF signal from the one state to the other state, wherein the pulse of the first RF signal is generated upon receiving a control signal from a computer, wherein the pulsing of the second RF signal is performed to synchronize the pulsing of the second RF signal with pulsing of the first RF signal.

5 . The method of claim 1 , wherein the second RF signal is pulsed from the one state to the other state when a predetermined power set point is applied to the second RF signal, wherein the second RF signal is pulsed from the other state to the one state when another predetermined power set point is applied to the second RF signal.

6 . The method of claim 1 , wherein the parameter is gamma, or forward power, or reflected power, or a voltage and current probe measurement, or a complex impedance, wherein the parameter is sensed at an output of an RF generator.

7 . A method comprising:
generating a first RF signal; sending the first RF signal to an impedance match network that is coupled to a plasma chamber; sensing a parameter indicating a change in an impedance of plasma within the plasma chamber, wherein the change in the impedance occurs when a state of a second RF signal changes from one state to another; and pulsing the first RF signal from one state to another in response to sensing the parameter indicating the change in the impedance.

8 . The method of claim 7 , wherein the parameter is sensed at an output of an RF generator that generates the second RF signal.

9 . The method of claim 7 , wherein the second RF signal is a low-frequency RF signal and the first RF signal is a high-frequency RF signal, wherein the high-frequency is greater than the low-frequency.

10 . The method of claim 7 , wherein the one state of the first RF signal is an on state and the other state of the first RF signal is an off state, wherein the one state of the second RF signal is an on state and the other state of the second RF signal is an off state, wherein the pulse of the second RF signal is generated upon receiving a control signal from a computer.

11 . The method of claim 7 , wherein the first RF signal is pulsed from the one state to the other state when a predetermined power set point is applied to the first RF signal, wherein the first RF signal is pulsed from the other state to the one state when another predetermined power set point is applied to the first RF signal, wherein the parameter is sensed at an output of an RF generator.

12 . 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 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.

13 . The method of claim 12 , 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.

14 . The method of claim 12 , 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.

15 . The method of claim 12 , further comprising receiving a trigger threshold value from a tool host computer, said trigger threshold value to enable circuitry in a sensor subsystem of said second RF generator to ascertain whether said first RF signal is pulsed high or pulsed low.

16 . The method of claim 12 , 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 a tool host computer.

17 . The method of claim 12 , 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.

18 . The method of claim 12 , 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 or represents an output impedance of said second RF generator.

19 . The method of claim 12 , 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.

20 . The method of claim 12 , wherein said second RF signal, when pulsed, pulses between a predefined high pulse value and a predefined low pulse value.

Assignees

• Lam Res Corp

Inventors

• Valcore Jr John C
• Lyndaker Bradford J
• Singh Harmeet

Classifications

• H01J37/32183 Primary

  Matching circuits · CPC title

• H01J37/32174

  Circuits specially adapted for controlling the RF discharge · CPC title

• H01J37/32146

  Amplitude modulation, includes pulsing · CPC title