PASSIVE CAPACITIVELY-COUPLED ELECTROSTATIC (CCE) PROBE ARRANGEMENT FOR DETECTING PLASMA INSTABILITIES IN A PLASMA PROCESSING CHAMBER

• US 20100033195A1
• Filed: 07/07/2009
• Published: 02/11/2010
• Est. Priority Date: 07/07/2008
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Nagai, Mikio, Booth, Jean-Paul, Keil, Douglas
• Granted Patent: US 8,179,152 B2
• Time in Patent Office: Days
• US Class Current: 324/663
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An arrangement for detecting plasma instability within a processing chamber of a plasma processing system during substrate processing is provided. The arrangement includes a probe arrangement, wherein the probe arrangement is disposed on a surface of the processing chamber and is configured to measure at least one plasma processing parameter. The probe arrangement includes a plasma-facing sensor and a measuring capacitor, wherein the plasma-facing sensor is coupled to a first plate of the measuring capacitor. The arrangement also includes a detection arrangement, which is coupled to a second plate of the measuring capacitor. The detection arrangement is configured to convert an induced current flowing through the measuring capacitor into a set of digital signals, the set of digital signals being processed to detect the plasma instability.

Claims

1. An arrangement for detecting plasma instability within a processing chamber of a plasma processing system during substrate processing, comprising:

a probe arrangement, wherein said probe arrangement is disposed on a surface of said processing clamber and is configured to measure at least one plasma processing parameter, wherein said probe arrangement includes

a plasma-facing sensor, and

a measuring capacitor, wherein said plasma-facing sensor is coupled to a first plate of said measuring capacitor; and

a detection arrangement, said detection arrangement is coupled to a second plate of said measuring capacitor, wherein said detection arrangement is configured to convert an induced current flowing through said measuring capacitor into a set of digital signals, said set of digital signals being processed to detect said plasma instability.

2. The arrangement of claim 1 wherein said plasma-facing sensor is disposed in an upper electrode.

3. The arrangement of claim 1 wherein said plasma-facing sensor is disposed on a chamber wall of said processing chamber.

4. The arrangement of claim 1 wherein said plasma-facing sensor is made of a conductive material.

5. The arrangement of claim 1 wherein said plasma-facing sensor is a capacitively-coupled electrostatic (CCE) probe head.

6. The arrangement of claim 1 wherein said detection arrangement includes

a current-to-voltage converter, wherein said current-to-voltage converter is configured for at least converting said current flowing through said probe arrangement into a set of analog voltage signals,

an analog-to-digital converter configured for at least converting said set of analog voltage signals into said set of digital signals, and

a signal processor, wherein said signal processor is configured for at least processing said set of digital signals to detect high frequency perturbations, said high frequency perturbations indicating said plasma instability.

7. The arrangement of claim 1 further including a tool control circuit, wherein said tool control circuit is configured for receiving a message from said detection arrangement when said plasma instability is detected, said tool control circuit is configured to apply correction actions to fix said plasma instability.

8. The arrangement of claim 1 further including a voltage measurement device coupled to said first plate of said measuring capacitor, wherein said voltage measurement device being configured for at least collecting voltage measurements and for measuring potential change of said plasma-facing sensor.

9. The arrangement of claim 8 wherein voltage measurements collected by said voltage measurement device is converted to a digital signal for signal processing to detect said plasma instability.

10. The arrangement of claim 1 further including a transformer, said transformer being coupled to said second plate of said measuring capacitor, wherein said transformer being configured for at least identifying perturbations in said induced current.

11. A method for detecting plasma instability within a processing chamber of a plasma processing system during substrate processing, comprising:

collecting a set of process data, said process data including induced current signals flowing through a measuring capacitor;

converting said induced current signals into a set of analog voltage signals;

converting said set of analog voltage signals into a set of digital signals; and

analyzing said set of digital signals to detect high frequency perturbations, said high frequency perturbations indicating said plasma instability.

12. The method of claim 11 further including comparing rate of change of said current signals to a pre-defined threshold, wherein said plasma instability exists if said rate of change is outside of said pre-defined threshold.

13. The method of claim 12 further including sending a message to a tool controller circuit when said plasma instability is detected, said tool control circuit is configured to apply correction actions to fix said plasma instability.

14. The method of claim 11 further including collecting voltage measurement data from a plasma-facing sensor to determine potential change during processing.

15. The method of claim 14 further including converting said voltage measurement data into a set of digital signals.

16. The method of claim 15 further including analyzing said set of digital signals to detect said high frequency perturbations, wherein said high frequency perturbations indicating said plasma instability.

17. The method of claim 16 further including comparing rate of change of said voltage signals to a pre-defined threshold, wherein said plasma instability exists if said rate of change is outside of said pre-defined threshold.

18. The method of claim 11 further including applying a set of periodic radio frequency (RF) pulse trains to said measuring capacitor and measuring current decay signals of said measuring capacitor.

19. The method of claim 18 further including applying an arc detection algorithm to detect said high frequency perturbations above said pre-determined threshold on said measuring capacitor'"'"'s current decay signals.

20. The method of claim 19 further including comparing rate of change of said current decay signals to a pre-defined threshold, wherein said plasma instability exists if said rate of change is outside of said pre-defined threshold.