Method and device utilizing plasma source for real-time gas sampling

• US 20060203239A1
• Filed: 03/27/2006
• Published: 09/14/2006
• Est. Priority Date: 11/29/2000
• Status: Active Grant

• Current Assignee: Lightwind Corp.
• Original Assignee: Lightwind Corp.
• Inventors: Powell, Gary, Hazard, Richard L.
• Granted Patent: US 7,202,946 B2
• Time in Patent Office: Days
• US Class Current: 356/316
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 1/2226 Sampling from a closed space, e.g. food package, head space
• CPC Class Codes: G01N 21/15 Preventing contamination of the components of the optical system or obstruction of the light path
• CPC Class Codes: G01N 21/68 using high frequency electric fields

Abstract

Aspects of the present invention provide novel methods and devices for sampling gas, exciting the sampled gas to emit radiation and detecting in real time from the emitted radiation a plurality of wave bands of an emission spectrum. Energy used to excite the sampled gas may be adjusted based on the detected wave bands. A process may be controlled in real time based on the detected wave bands. Novel interfaces may be used to display portions of the detected wave bands. A known flow of a reference gas may be included in the flow of sampled gases and an unknown flow of an unknown flow gas determined.

Claims

1. A system including:

a spectrographic system with a plasma source, including a window for collection of radiation emitted from plasma generated by the plasma source, positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber;

a supplemental gas source that supplies ionizable gas to the plasma source outside the reaction chamber; and

control logic to activate the gas source and energize the plasma source for a time sufficient to clean the window, while the spectrographic system is otherwise idle.

2. The spectrographic system of claim 1, wherein the ionizable gas contains nitrogen.

3. The spectrographic system of claim 1, wherein the ionizable gas contains oxygen.

4. The spectrographic system of claim 1, wherein the spectrographic system is utilized to monitor a deposition process and the control logic activates the gas source and the plasma source in a self-cleaning process shortly after monitoring the deposition process.

5. The spectrographic system of claim 1, wherein the gas source supplies the ionizable gas to an inlet to the plasma source through which the gas analyzed from the reaction chamber is received.

6. The spectrographic system of claim 1, wherein the gas source supplies the ionizable gas to an additional inlet to the plasma source proximate to the window, separate from an inlet through which the gas analyzed from the reaction chamber is received.

7. The spectrographic system of claim 1, wherein the control logic energizes the plasma source with more energy for cleaning than used for spectrographic analysis.

8. A method applied to a spectrographic system with a plasma source, of cleaning a window for collection of radiation emitted from plasma generated by the plasma source, the spectrographic system positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber, the method including:

supplying a supplemental ionizable gas to the plasma source outside the reaction chamber; and

activating the gas source and energizing the plasma source for a time sufficient to clean the window, while the spectrographic system is otherwise idle.

9. The method of claim 8, wherein the ionizable gas contains nitrogen.

10. The method of claim 8, wherein the ionizable gas contains oxygen.

11. The method of claim 8, further including:

monitoring a deposition process in the reaction chamber with the spectrographic system;

wherein activating the gas source in a self-cleaning process follows monitoring the deposition process.

12. The method of claim 8, wherein the gas source supplies the ionizable gas to an inlet to the plasma source through which the gas analyzed from the reaction chamber is received.

13. The method of claim 8, wherein the gas source supplies the ionizable gas to an additional inlet to the plasma source proximate to the window, separate from an inlet through which the gas analyzed from the reaction chamber is received.

14. The method of claim 8, wherein energizing the plasma source applies more energy for cleaning than used for spectrographic analysis.

15. A system including:

a spectrographic system with a plasma source, including a window for collection of radiation emitted from plasma generated by the plasma source, positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber;

wherein the spectrographic system is used to monitor a process that includes a process step and a purge step; and

control logic to energize the plasma source during the purge step for a time sufficient to clean the window of materials from the process step.

16. The spectrographic system of claim 15, wherein the purge gas contains nitrogen.

17. The spectrographic system of claim 15, wherein the purge gas contains oxygen.

18. The spectrographic system of claim 15, wherein the control logic energizes the plasma source with more energy for self-cleaning than used for spectrographic analysis.

19. A method applied to a spectrographic system with a plasma source, of cleaning a window for collection of radiation emitted from plasma generated by the plasma source, the spectrographic system positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber, the method including:

applying the spectrographic system to monitor a process in the reaction chamber that includes a process step and a purge step; and

energizing the plasma source during the purge step for a time sufficient to clean the window.

20. The spectrographic system of claim 19, wherein the purge gas contains nitrogen.

21. The spectrographic system of claim 19, wherein the purge gas contains oxygen.

22. The spectrographic system of claim 19, wherein energizing the plasma source applies more energy for self-cleaning than used for spectrographic analysis.

23. A system including:

a spectrographic system with a plasma source, including a window for collection of radiation emitted from plasma generated by the plasma source, positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber; and

at least one heating element that applies sufficient heat for the window to remain substantially clear of deposited material.

24. The spectrographic system of claim 23, wherein the heating element is proximate to the window and applies heat in a vicinity of the window.

25. The spectrographic system of claim 23, wherein the plasma source includes an excitation chamber and the heating element is proximate to and applies heat to the excitation chamber and the window.

26. The spectrographic system of claim 23, further including an exhaust sample line in gaseous communication with the plasma source and the reaction chamber, wherein the heating element applies heat to the exhaust sample line.

27. A method applied to a spectrographic system with a plasma source, of cleaning a window for collection of radiation emitted from plasma generated by the plasma source, the spectrographic system positioned outside of a reaction chamber to analyze gas from the reaction chamber as a process proceeds in the reaction chamber, the method including:

applying sufficient heat for the window to remain substantially clear of deposited material.

28. The method of claim 27, wherein the plasma source further includes an excitation chamber, the method further including applying the heat to the excitation chamber and the window.

29. The method of claim 27, wherein the plasma source further includes an exhaust sample line in gaseous communication with the plasma source and the reaction chamber, the method further including applying the heat to the exhaust sample line.