Pedestal heat transfer and temperature control

• US 7,941,039 B1
• Filed: 09/06/2007
• Issued: 05/10/2011
• Est. Priority Date: 07/18/2005
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Kamian, George, Rivkin, Michael, Woytowitz, Peter, Gentile, Stephen V., Roham, Sassan, Shrinivasan, Krishnan
• Primary Examiner(s): ROBINSON, DANIEL LEON
• Application Number:
  US11/851,310
• Time in Patent Office: 1,342 Days
• Field of Search: 392/416, 392407-440, 219/405, 118/724, 118/725, 118/726
• US Class Current: 392/416
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01L 21/67103 mainly by conduction
• CPC Class Codes: H01L 21/67115 mainly by radiation

Abstract

Provided herein are assemblies that, when coupled to an object, are capable of keeping the object at a uniform elevated temperature while removing large amounts of heat from an external source. Applications include various integrated circuit fabrication processes that use such external sources to expose wafers to radiation. In certain embodiments, the assemblies include a pedestal for supporting the wafer or other object. In certain embodiments, the assemblies include a calibrated heat resistance that allows heat be conducted away from the pedestal and wafer to maintain the desired set-point temperature. In certain embodiments, the pedestal may have one or more protrusions used to dissipate or transfer heat from the pedestal to a heat sink. Also, in certain embodiments, the pedestal surface is configured to have a spectral reflectivity of desired values in such way as to reflect the wavelengths that are emitted by an external radiant heat source.

Claims

1. An assembly for maintaining a workpiece exposed to an external heat source at a uniform temperature comprising a heat transfer assembly, said heat transfer assembly comprising:

a chamber housing;

a pedestal located in the chamber for supporting the workpiece;

a source of radiation located above the workpiece for exposing the workpiece to radiation,

a heat sink for absorbing or dissipating a calibrated quantity of heat from the source of radiation;

a heat resistant path located between the wafer and the heat sink, said heat resistant path having a heat resistance calibrated such that the workpiece temperature is maintained, and

one or more protrusions from the pedestal, wherein said protrusions comprise at least part of the calibrated heat resistant path.

2. The assembly of claim 1 wherein one or more protrusions are connected to the heat sink.

3. The assembly of claim 1 further comprising one or more pedestal supports, wherein said pedestal supports comprise at least part of the calibrated heat resistant path.

4. The assembly of claim 1 wherein the heat sink includes at least part of one more chamber walls.

5. The assembly of claim 1 wherein the heat sink comprises cooling channels.

6. The assembly of claim 1 wherein the pedestal is configured to move between a first position and a second position, said second position closer to the heat sink than said first position.

7. An apparatus for exposing a workpiece to radiation comprising:

a) a source of radiation located above said workpiece, said source configured to emit radiation at a peak intensity of a defined spectral range; and

b) a pedestal for supporting said workpiece;

wherein the top surface of the pedestal is configured to reflect at least 30% of the of the radiation emitted in the defined spectral range.

8. The apparatus of claim 7 wherein the source of radiation emits infra-red radiation.

9. The apparatus of claim 7 wherein the source of radiation emits ultraviolet radiation.

10. The apparatus of claim 7 wherein the top surface of the pedestal is a machined metal.

11. The apparatus of claim 7 wherein the top surface of the pedestal has a mirror polish.

12. The apparatus of claim 7 further comprising a cooling element for removing heat generated by the source of radiation, said cooling element using a coolant having a boiling temperature of less than 200°

C. as a heat-transfer fluid.

13. The apparatus of claim 7 further comprising a heat resistant layer located between the cooling element and the workpiece;

said layer having a calibrated heat resistance such that coolant in the cooling element does not boil and the workpiece temperature is maintained.

14. An assembly for maintaining a workpiece exposed to an external heat source at a uniform temperature comprising a heat transfer assembly, said heat transfer assembly comprising:

a) a source of radiation located above the workpiece for exposing the workpiece to radiation,

b) a heat sink for absorbing or dissipating a calibrated quantity of heat from the source of radiation; and

c) a pedestal for supporting the workpiece, said pedestal comprising one or more protrusions for transferring the calibrated quantity of heat to the heat sink.

15. An apparatus for exposing a workpiece to radiation comprising:

a) a source of radiation located above said workpiece, said source configured to emit radiation at a peak intensity of a defined spectral range;

b) a pedestal for supporting said workpiece;

wherein the top surface of the pedestal is configured to reflect the radiation of all or part of the defined spectral range; and

c) a cooling element for removing heat generated by the source of radiation, said cooling element using a coolant having a boiling temperature of less than 200°

C. as a heat-transfer fluid.