Method for operation instability detection in a surface wave plasma source

• US 10,651,017 B2
• Filed: 01/26/2017
• Issued: 05/12/2020
• Est. Priority Date: 06/30/2016
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Voronin, Sergey, Marion, Jason, Ranjan, Alok
• Primary Examiner(s): Dhingra, Rakesh K
• Application Number:
  US15/416,422
• Publication Number:
  US 20180005805A1
• Time in Patent Office: 1,202 Days
• Field of Search: 15634524-34528, 15634541, 118723 MW
• CPC Class Codes: G01N 21/73 using plasma burners or torches
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: H01J 2237/3341 Reactive etching
• CPC Class Codes: H01J 37/32128 using particular waveforms, e.g. polarised waves
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/3299 Feedback systems
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Provided are methods and systems for operation instability detection in a surface wave plasma source. In an embodiment a system for plasma processing may include a surface wave plasma source configured to generate a plasma field. The system may also include an optical sensor configured to generate information characteristic of optical energy collected in a region proximate to the surface wave plasma source. Additionally, the system may include a sensor logic unit configured to detect a region of instability proximate to the surface wave plasma source in response to the information generated by the optical sensor.

Claims

1. A system for plasma processing comprising:

a surface wave plasma source configured to generate a plasma field;

wherein the surface wave plasma source further comprises a plasma distribution plate having a plurality of regions of non-uniformity on a surface of the plasma distribution plate, wherein the plurality of regions of non-uniformity comprise dimples formed on the surface of the plasma distribution plate;

a plurality of optical sensors configured to generate information characteristic of optical energy collected by way of a plurality of optical fibers each disposed on an interior surface of a respective one of the dimples; and

a sensor logic unit configured to detect a region of instability in response to the information generated by the plurality of optical sensors,

wherein the sensor logic unit comprises a comparator, and wherein the sensor logic unit generates an instability signal in response to a determination that;

(i) a difference between a sensor signal of one of the optical sensors and a reference signal exceeds a threshold value, or

(ii) a difference between one sensor signal of one of the optical sensors and another sensor signal of another of the optical sensors exceeds a threshold value.

2. The system of claim 1 wherein the plurality of regions of non-uniformity comprise dimples formed on the surface of the plasma distribution plate.

3. The system of claim 1 wherein the sensor logic unit comprises an amplifier.

4. The system of claim 1 wherein the sensor logic unit comprises a plurality of amplifiers, each configured to amplify a signal generated by one of the plurality of optical sensors.

5. The system of claim 1 wherein the comparator is configured to compare a plurality of sensor signals with the reference signal, each sensor signal being generated by one of the plurality of optical sensors.

6. The system of claim 1 further comprising a source controller, the source controller configured to control a parameter of power supplied to the surface wave plasma source in response to feedback received from the sensor logic unit.

7. The system of claim 1 further comprising a plasma etch chamber coupled to the surface wave plasma source, the plasma etch chamber being configured to contain a plasma field generated by the surface wave plasma source and a wafer support disposed within the plasma etch chamber, the wafer support configured to receive a semiconductor wafer for processing.

8. The system of claim 1, wherein the instability signal includes a notification to an operator or an alarm.

9. A system for plasma processing comprising:

a surface wave plasma source configured to generate a plasma field;

at least one optical sensor configured to generate information characteristic of optical energy collected in a region proximate to the surface wave plasma source;

a sensor logic unit configured to detect a region of instability proximate to the surface wave plasma source in response to the information generated by the at least one optical sensor;

wherein the surface wave plasma source further comprises a plasma distribution plate having a plurality of regions of non-uniformity on a surface of the plasma distribution plate;

wherein the plurality of regions of non-uniformity comprise dimples formed on the surface of the plasma distribution plate; and

the system further comprising plural optical fibers coupled to the plasma distribution plate and disposed in regions proximate different ones of the dimples formed on the surface of the plasma distribution plate, and the optical fibers are configured to collect the optical energy from plasma generated in the regions proximate to the dimples formed on the surface of the plasma distribution plate, wherein a first end of each of the optical fibers is disposed on an interior surface of a respective one of the dimples.

10. The system of claim 9 wherein the at least one optical sensor comprises a light sensitive diode disposed proximate to the optical fibers.

11. The system of claim 10 wherein the at least one optical sensor comprises a plurality of light sensitive diodes disposed proximate one end of each of the plurality of optical fibers.

12. The system of claim 9 wherein at least one of the optical fibers is disposed along an internal axis of the plasma distribution plate.

13. The system of claim 9, wherein the at least one optical sensor generates plural sensor signals corresponding to the optical energy collected at the different regions proximate different ones of the dimples, and the sensor logic generates an instability signal in response to a determination that:

(i) a difference between one of the plurality of sensor signals and a reference signal exceeds a threshold value, or

(ii) a difference between one of the plurality of sensor signals and another of the plurality of sensor signals exceeds a threshold value.

14. A method for plasma processing comprising:

generating a plasma field with a surface wave plasma source;

generating information characteristic of optical energy collected in a region proximate to the surface wave plasma source with at least one optical sensor;

detecting, with a sensor logic unit, a region of instability proximate to the surface wave plasma source in response to the information generated by the at least one optical sensor;

wherein the generating information includes collecting information pertaining to optical energy at plural different regions proximate to the surface wave plasma source and providing the information from the plural different regions to the at least one optical sensor, and the at least one optical sensor generates sensor signals corresponding to the information collected at the plural different regions proximate to the surface wave plasma source;

wherein the surface wave plasma source includes a plasma distribution plate having plural regions of non-uniformity, wherein the plurality of regions of non-uniformity comprise dimples formed on the surface of the plasma distribution plate, and the collecting information at plural different regions includes collecting information by way of a plurality of optical fibers each disposed on an interior surface of a respective one of the dimples; and

the method further including generating an instability signal in response to a determination of at least one of;

(i) a difference between a sensor signal and a reference signal exceeds a threshold value, or

(ii) a difference between a sensor signal corresponding to one region of the plural regions of non-uniformity and another sensor signal corresponding to another region of the plural regions of non-uniformity exceeds a threshold value.

15. The method of claim 14, wherein the instability signal includes a notification sent to an operator or an alarm.

16. The method according to claim 14, wherein the plural optical fibers are connected to the at least one optical sensor.