Advanced rapid thermal processing (RTP) using a linearly-moving heating assembly with an axisymmetric and radially-tunable thermal radiation profile

• US 20040060917A1
• Filed: 09/30/2002
• Published: 04/01/2004
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: Axcelis Technologies Incorporated
• Original Assignee: Axcelis Technologies Incorporated
• Inventors: Liu, Yong, Hebb, Jeff P.
• Granted Patent: US 6,768,084 B2
• Time in Patent Office: Days
• US Class Current: 219/390
• CPC Class Codes: F27B 17/0025 Especially adapted for treating semiconductor wafers
• CPC Class Codes: F27D 11/00 Arrangement of elements for electric heating in or on furnaces electric heating per se H05B
• CPC Class Codes: F27D 19/00 Arrangements of controlling devices
• CPC Class Codes: F27D 21/0014 Devices for monitoring temperature
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/67115 mainly by radiation
• CPC Class Codes: H01L 21/67248 Temperature monitoring

Abstract

The present invention is directed to a semiconductor thermal processing system and a method for thermally processing a semiconductor substrate. According to one aspect of the present invention, a semiconductor thermal processing system and associated method is disclosed which provides a heater chamber and a process chamber, wherein the heater chamber and process chamber are environmentally isolated from one another by a thermally-transparent plate. A heater assembly comprising one or more quasi-continuous heater elements is situated in the heater chamber, whereby a linear translation assembly is operable to linearly translate the heater assembly with respect to the process chamber. A power supply is operable to provide electric current to the one or more heater elements, thereby emitting thermal radiation that transmits through the thermally-transparent plate toward a substrate situated within the process chamber. One or more temperature sensors are operable to measure one or more temperatures associated with one or more respective locations on the substrate. A controller operably coupled to the heater assembly, linear translation assembly, and the one or more temperature sensors is operable to control the thermal radiation emitted by the one or more heater elements, as well as a distance between the heater assembly and the substrate. The control is based, at least in part, on the one or more measured temperatures.

Claims

1. A thermal processing system, comprising:

a heater chamber;

a process chamber;

a generally thermally-transparent plate separating the heater chamber and the process chamber;

a heater assembly disposed within the heater chamber, the heater assembly comprising one or more quasi-continuous heater elements, wherein the one or more heater elements are operable to emit thermal radiation that transmits through the thermally-transparent plate toward a substrate disposed in the process chamber;

one or more power supplies operable to provide electric current to the one or more quasi-continuous heater elements;

a translation assembly operably coupled to the heater assembly, wherein the translation assembly is operable to vary a distance between the heater assembly and the substrate;

one or more temperature sensors operable to measure one or more substrate temperatures at one or more respective locations associated with the substrate; and

a controller operably coupled to the heater assembly, the one or more temperature sensors, and the translation assembly, wherein the controller is operable to control the thermal radiation emitted by the one or more heater elements and the distance between the heater assembly and the substrate based, at least in part, on the substrate temperature measured at the one or more locations on the substrate.

2. The thermal processing system of claim 1, wherein the one or more heater elements comprise one or more quasi-continuous, coaxial heater rings.

3. The thermal processing system of claim 2, wherein the one or more heater rings are axisymmetric with respect to an axis normal to the substrate.

4. The thermal processing system of claim 2, wherein a total thermal radiation profile of the heater elements are radially-tunable, wherein the thermal radiation emitted by each of the one or more heater rings is individually controllable.

5. The thermal processing system of claim 2, wherein the one or more heater rings are coaxially in a common plane.

6. The thermal processing system of claim 2, wherein at least one heater ring is closer to or further from the substrate than other heater rings.

7. The thermal processing system of claim 2, where at least one of the heater rings is adapted to be selectably tilted with respect to a direction generally normal to the substrate.

8. The thermal processing system of claim 1, wherein the one or more heater elements comprise an electric conductor or a semiconductor.

9. The thermal processing system of claim 1, wherein the heater chamber comprises a port for drawing a vacuum or delivering an inert or non-reactive gas therethrough.

10. The thermal processing system of claim 1, wherein the process chamber comprises a port for drawing a vacuum or a port delivering a process gas or inert gas therethrough.

11. The thermal processing system of claim 1, wherein the heater chamber further comprises an auxiliary heater ring, the auxiliary heater ring being coaxial with the substrate and having a diameter approximately equal to or greater than a diameter of the substrate.

12. The thermal processing system of claim 11, wherein the auxiliary heater ring is stationary with respect to the process chamber.

13. The thermal processing system of claim 11, wherein a thermal radiation of the auxiliary heater ring is operably controlled, at least partially, in response to a target temperature of the substrate, a measured substrate temperature, and a distance between the heater assembly and the substrate.

14. The thermal processing system of claim 1, wherein the heater chamber further comprises a thermal shield, the thermal shield is operable to direct or reflect thermal energy toward the heater elements and the substrate.

15. The thermal processing system of claim 14, wherein the thermal shield is operably coupled to the heater assembly and is actively cooled or heated.

16. The thermal processing system of claim 1, wherein the translation assembly is operably coupled to the heater assembly, wherein the translation assembly is operable to linearly move the heater assembly along a direction perpendicular to the substrate inside the process chamber, thereby varying the distance between the heater assembly and the substrate according to the control signal from the controller.

17. The thermal processing system of claim 16, wherein the translation assembly is mechanically or magnetically coupled to the heater assembly.

18. The thermal processing system of claim 16, wherein the controller is operable to provide control data to the translation assembly, wherein the translation assembly is operable to vary the distance between the heater assembly and the substrate based on the control data.

19. The thermal processing system of claim 16, wherein the heater chamber further comprises at least one motion mechanism that linearly moves the heater assembly while maintaining a vacuum integrity of the heater chamber.

20. The thermal processing system of claim 19, wherein the heater chamber further comprises a bellows, elastomer seal or a magnetic transporter to maintain the vacuum integrity of the heater chamber.

21. The thermal processing system of claim 16, wherein the translation assembly further comprises a motion generation device comprising a servo motor, a piezoelectric drive, or a pneumatic pump.

22. The thermal processing system of claim 16, wherein the translation assembly further comprises a positional sensing system, wherein a linear position of the heater assembly is measured and fed back to the controller.

23. The thermal processing system of claim 1, wherein the power supply comprises a single power supply operable to provide electric power to a plurality of heater elements according to one or more control signals from the controller.

24. The thermal processing system of claim 1, wherein the one or more temperature sensors comprise one or more remote temperature sensors or one or more contact-type temperature sensors.

25. The thermal processing system of claim 24, wherein the process chamber comprises one or more optical paths for remote sensing of one or more substrate temperatures at the one or more locations using one or more remote temperature sensors.

26. The thermal processing system of claim 24, wherein the process chamber comprises one or more electrical paths for conducting electrical signals of one or more contact-type temperature sensors.

27. The thermal processing system of claim 1, wherein the heater chamber comprises a shutter located above the thermally-transparent plate, wherein the shutter is operable to close and to block thermal radiation from the heater assembly to the substrate when the heater assembly is retracted sufficiently from the substrate.

28. The thermal processing system of claim 1, wherein the controller further comprises a single-channel feedback control system.

29. The thermal processing system of claim 28, wherein the controller further comprises a multi-channel closed-loop feedback control system.

30. The thermal processing system of claim 1, further comprising a control computer, wherein the controller in conjunction with the control computer comprises electrical and electronic circuits, control programs and algorithms operable to control the thermal radiation emitted by the one or more heater elements, based on the measured one or more temperatures at the one or more locations, a desired substrate temperature versus time profile and a process gas composition versus time profile.

31. A method of thermally processing a substrate, comprising:

establishing an initial thermal radiation profile of a heater assembly by applying an initial set of electrical powers to one or more quasi-continuous heater elements of said heater assembly in a heater chamber;

loading said substrate into a process chamber and establishing an initial gas ambient or vacuum;

opening a shutter in said heater chamber and moving said heater assembly towards said substrate so that thermal radiation from said heater assembly transmits through a thermally-transparent plate onto said substrate in said process chamber;

measuring a distance between said substrate and said heater assembly, and measuring one or more temperatures at one or more locations of said substrate;

adjusting said distance, said electrical powers for said heater elements or said gas ambient based upon a desired temperature versus time profile, a desired temperature uniformity of said substrate, a desired process gas composition versus time profile, the measured distance and measured temperatures; and

moving said heater assembly to home position, closing said shutter and unloading said substrate from said process chamber.

32. The method of claim 31, further comprising repeating the measurement of the distance and the temperatures, and adjusting the distance and electrical powers throughout a thermal processing period of the substrate.

33. The method of claim 31, wherein the measuring and adjusting occurs concurrently with the establishment of the gas ambient in the process chamber, wherein a process gas is employed in a thermal processing of the substrate.

34. The method of claim 31, wherein determining the adjustment to said electrical powers comprises using multi-channel temperature input and multi-channel electrical power output, or single-channel temperature input and multi-channel electrical power output closed-loop feedback control.

35. The method of claim 31, wherein determining the adjustment to said distance comprises comparison of one or more desired temperatures and temperature profiles with the one or more measured temperatures and temperature profiles of said substrate at different locations.

36. The method of claim 31, where at least one of said distance, said electrical powers to said heater elements and said gas ambient in said process chamber is controlled in real-time according to pre-determined profiles or conditions for thermal processing.

37. The method of claim 31, wherein determining the adjustment to said distance and said electric powers or said gas ambient comprises utilizing mathematical algorithms, physical models, chemical models, or automatic data acquisition and process control via a computer.

38. The method of claim 31, further comprising moving the heater assembly between a home position and a maximal heating position to said substrate, wherein the former is further than the latter from said substrate.

39. The method of claim 31, wherein the adjustment of the distance comprises linearly moving the heater assembly, and wherein the linear motion of said heater assembly is used to control a heating level of said substrate in said process chamber.

40. The method of claim 31, wherein said electrical powers applied to said heater elements of said heater assembly are adjusted or tuned independently to control the radial profile of the thermal radiation of said heater assembly for desired temperature uniformity across said substrate.

41. The method of claim 31, the adjustment of said thermal radiation profile of said heater assembly includes the operation of tilting one or more heating rings in one or more respective directions as conventionally defined by polar and azimuthal angles.

42. The method of claim 31, wherein said distance versus time profile and said electrical powers versus time profiles applied to said heater elements are determined by a prior optimization procedure performed on one or more test substrates.

43. The method of claim 31, further comprising forming a vacuum in the process chamber one or more times, before, during or after a thermal processing cycle.

44. The method of claim 31, wherein measuring the one or more temperatures at the one or more locations associated with the substrate comprises utilizing one or more non-contact or remote temperature sensors, or one or more contact-type temperature sensors deployed onto or about the substrate

45. The method of claim 31, wherein measuring the one or more temperatures at the one or more locations associated with the substrate comprises using a multi-channel pyrometer.

46. The method of claim 31, wherein each of the one or more heater rings are individually movable with respect to the substrate in the process chamber.

47. A thermal processing system, comprising:

one process chamber; and

two or more heater assemblies, wherein the substrate under processing is sandwiched between the two or more heater assemblies.

48. The system of claim 47, wherein a thermal radiation profile of at least one of the two or more heater assemblies is radially-tunable or linearly-moving.

49. A thermal processing system, comprising:

a heater chamber;

a process chamber;

a generally thermally-transparent plate separating the heater chamber and the process chamber;

a heater assembly disposed within the heating chamber, the heater assembly comprising one or more discrete and independently-movable heater elements, wherein the one or more heater elements are operable to emit thermal radiation that transmits through the thermally-transparent plate toward a substrate disposed in the process chamber;

one or more power supplies operable to provide electric current to the one or more quasi-continuous heater elements;

a translation assembly operably coupled to the heater assembly, wherein the translation assembly is operable to vary a distance between the discrete heater elements and the substrate;

one or more temperature sensors operable to measure one or more substrate temperatures at one or more respective locations associated with the substrate; and

a controller operably coupled to the heater assembly, the one or more temperature sensors, and the translation assembly, wherein the controller is operable to control the thermal radiation emitted by the one or more heater elements and the distance between the heater elements and the substrate based, at least in part, on the one or more substrate temperatures measured at the one or more locations on the substrate.