REDUNDANT TEMPERATURE SENSOR FOR SEMICONDUCTOR PROCESSING CHAMBERS

• US 20090159000A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM America Incorporated (ASM International NV)
• Inventors: Jacobs, Loren, Kleshock, Mark, Aggarwal, Ravinder
• Granted Patent: US 7,993,057 B2
• Time in Patent Office: Days
• US Class Current: 118/666
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 7/04 the object to be measured not forming one of the thermoelectric materials
• CPC Class Codes: H01L 21/67248 Temperature monitoring

Abstract

Systems are provided for measuring temperature in a semiconductor processing chamber. Embodiments provide a multi-junction thermocouple comprising a first junction and a second junction positioned to measure temperature at substantially the same portion of a substrate. A controller may detect failures in the first junction, the second junction, a first wire pair extending from the first junction, or a second wire pair extending from the second junction. The controller desirably responds to a detected failure of the first junction or first wire pair by selecting the second junction and second wire pair. Conversely, the controller desirably responds to a detected failure of the second junction or second wire pair by selecting the first junction and first wire pair. Systems taught herein may permit accurate and substantially uninterrupted temperature measurement despite failure of a junction or wire pair in a thermocouple.

Claims

1. A temperature control system for controlling temperature in a semiconductor processing chamber, comprising:

a controller for controlling heat inputs into the processing chamber; and

a multi-junction thermocouple in communication with the controller, the multi-junction thermocouple comprising;

a first junction positioned to measure temperature at a portion of a substrate;

a first wire pair extending from the first junction;

a second junction positioned to measure temperature at substantially the same portion of the substrate; and

a second wire pair extending from the second junction.

2. The temperature control system of claim 1, wherein the first and second junctions are positioned to measure temperature at a center of the substrate.

3. The temperature control system of claim 1, wherein the first and second junctions are positioned to measure temperature at a location more than 1 mm from a center of the substrate.

4. The temperature control system of claim 1, wherein the first and second junctions are disposed within 1 mm of each other.

5. The temperature control system of claim 1, wherein the first and second junctions are disposed within 0.5 mm of each other.

6. The temperature control system of claim 1, wherein the first and second junctions are disposed within 0.25 mm of each other.

7. The temperature control system of claim 1, wherein the first and second junctions are coincident.

8. The temperature control system of claim 1, wherein the controller is configured to adjust heat inputs into the processing chamber based on measurements from the multi-junction thermocouple, and wherein the controller is configured to selectively receive measurements from the first junction, the second junction, or the first and second junctions.

9. The temperature control system of claim 8, wherein the controller is configured for detecting a failure in at least one of the (1) first junction and first wire pair and (2) second junction and second wire pair.

10. The temperature control system of claim 9, wherein the controller uses measurements from the second junction to detect failures in the first junction or the first wire pair.

11. The temperature control system of claim 9, wherein the controller is configured to respond to a detection of a failure of the first junction or the first wire pair by ceasing to use temperature measurements from the first junction for adjusting said heat inputs into the chamber.

12. The temperature control system of claim 11, wherein the controller is configured to respond to said failure by ceasing to receive measurements from the first junction.

13. The temperature control system of claim 11, wherein the controller is configured to respond to said failure by using temperature measurements from the second junction for adjusting said heat inputs into the chamber without exposing the semiconductor processing chamber to ambient temperatures.

14. The temperature control system of claim 11, wherein the controller is configured to respond to said failure by using temperature measurements from the second junction for adjusting said heat inputs into the chamber halting the semiconductor processing.

15. The temperature control system of claim 1, wherein the semiconductor processing chamber is configured to carry out epitaxial deposition.

16. A multi-junction thermocouple for use in a semiconductor processing chamber, comprising:

a first junction;

a first wire pair joined at the first junction;

a second junction disposed less than 1 mm from the first junction; and

a second wire pair joined at the second junction.

17. The multi-junction thermocouple of claim 16, wherein the second junction is disposed within 0.5 mm of the first junction.

18. The multi-junction thermocouple of claim 16, wherein the second junction is disposed within 0.25 mm of the first junction.

19. The multi-junction thermocouple of claim 16, wherein the first and second junctions are coincident.

20. The multi-junction thermocouple of claim 16, wherein the first and second junctions are disposed less than 1 mm from a center axis of a substrate in the chamber.

21. The multi-junction thermocouple of claim 16, wherein the first and second junctions are disposed more than 1 mm from a center axis of a substrate in the chamber.

22. The multi-junction thermocouple of claim 16, wherein the first and second junctions are disposed within a single sheath.

23. The multi-junction thermocouple of claim 22, wherein the sheath comprises quartz.

24. The multi-junction thermocouple of claim 22, wherein the first and second junctions are disposed within a single coating over the sheath.

25. The multi-junction thermocouple of claim 24, wherein the coating comprises a silicon carbide layer.

26. The multi-junction thermocouple of claim 24, wherein the coating comprises a silicon nitride layer.

27. The multi-junction thermocouple of claim 24, wherein the coating has a thickness between approximately 500 to 5000 angstroms.

28. The multi-junction thermocouple of claim 27, wherein the coating has a thickness between approximately 1500 to 2500 angstroms.

29. The multi-junction thermocouple of claim 24, wherein the coating is formed by a sputter process.

30. The multi-junction thermocouple of claim 24, wherein the coating is formed by a chemical vapor deposition process.

31. A temperature detection system comprising a thermocouple, the thermocouple comprising:

a junction;

a first conductor coupled to the junction, the first conductor being formed of a first material; and

second and third conductors coupled to the junction, the second and third conductors being formed of a second material different than the first material.

32. The temperature detection system of claim 31, further comprising a fourth conductor formed of the second material, the fourth conductor being coupled to the junction.

33. The temperature detection system of claim 31, wherein the first material is platinum and the second material is platinum and rhodium.

34. The temperature detection system of claim 31, further comprising a controller for determining a temperature measurement from the thermocouple, wherein the controller is configured for monitoring the first, second and third conductors and for detecting a failure in at least one of the conductors, and wherein the controller is configured to respond to a detection of a failure of the first, second or third conductor by ceasing to use inputs from the failed conductor for determining a temperature measurement from the thermocouple.

35. The temperature detection system of claim 31, wherein the thermocouple is configured for use in a semiconductor processing chamber.

36. A semiconductor processing apparatus, comprising:

a reaction chamber;

a susceptor for supporting a substrate within the chamber;

a shaft assembly for supporting the susceptor; and

a multi-junction thermocouple, comprising;

a first junction positioned to measure temperature at a position immediately adjacent to a substrate; and

a second junction positioned to measure temperature at substantially the same position immediately adjacent to the substrate.

37. The apparatus of claim 36, wherein at least a portion of the multi-junction thermocouple is disposed within the shaft.

38. The apparatus of claim 36, wherein the first and second junctions are positioned between the substrate and the shaft.

39. The apparatus of claim 38, wherein the first and second junctions are positioned within 1 mm of a center axis of the substrate.

40. The apparatus of claim 36, wherein the reactor is a chemical vapor deposition chamber.

41. The apparatus of claim 36, wherein the reactor is a single wafer, cold wall reaction chamber.

42. The apparatus of claim 36, further comprising a controller configured to adjust heat inputs into the reaction chamber based at least in part on measurements from the first junction and further configured to respond to a detected failure in the first junction or in a pair of wires extending from the first junction by adjusting the heat inputs based on measurements from the second junction and by ceasing to use measurements from the first junction.

43. A method of measuring temperature in a semiconductor processing chamber, comprising:

providing a multi-junction thermocouple inside the chamber, the multi-junction thermocouple comprising a first junction, a first wire pair operatively connected to the first junction, a second junction disposed within 1 mm of the first junction, and a second wire pair operatively connected to the second junction; and

receiving temperature measurements from the multi-junction thermocouple, wherein the measurements can be selectively received from the first junction, the second junction, or both of the junctions.

44. The method of claim 43, further comprising programming a controller to detect failures in the first junction, the second junction, the first wire pair, or the second wire pair.

45. The method of claim 44, further comprising programming the controller to adjust heat inputs into the chamber based at least partly on temperature measurements received from the first and/or second junctions.

46. The method of claim 45, further comprising programming the controller to respond to a detected failure of the first junction or the first wire pair by ceasing to receive measurements from the first junction and by adjusting said heat inputs based on measurements received from the second junction.