Wafer support system

• US 6,203,622 B1
• Filed: 01/11/2000
• Issued: 03/20/2001
• Est. Priority Date: 09/01/1995
• Status: Expired due to Term

• Current Assignee: ASM America Incorporated (ASM International NV)
• Original Assignee: ASM America Incorporated (ASM International NV)
• Inventors: van der Jeugd, Cornelius A., Halpin, Michael W., Foster, Derrick W., Jacobs, Loren R., Hawkins, Mark R., Wengert, John F., Vyne, Robert M.
• Primary Examiner(s): LUND, JEFFRIE ROBERT
• Application Number:
  US09/480,918
• Time in Patent Office: 434 Days
• Field of Search: 118/715, 118/725, 118/728, 118/730, 118/500
• US Class Current: 118/730
• CPC Class Codes: C23C 16/455 characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
• CPC Class Codes: C23C 16/45521 the gas, other than thermal contact gas, being introduced the rear of the substrate to flow around its periphery
• CPC Class Codes: C23C 16/4584 the substrate being rotated
• CPC Class Codes: C23C 16/4586 Elements in the interior of the support, e.g. electrodes, heating or cooling devices
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/68735 characterised by edge profile or support profile
• CPC Class Codes: H01L 21/6875 characterised by a plurality of individual support members, e.g. support posts or protrusions
• CPC Class Codes: H01L 21/68785 characterised by the mechanical construction of the susceptor, stage or support

Abstract

A wafer support system comprising a segmented susceptor having top and bottom sections and gas flow passages therethrough. A plurality of spacers projecting from a recess formed in the top section of the susceptor support wafers in spaced relationship with respect to the recess. A sweep gas is introduced to the bottom section of the segmented susceptor and travels through the gas flow passages to exit in at least one circular array of outlets in the recess and underneath the spaced wafer. The sweep gas travels radially outward between the susceptor and wafer to prevent back-side contamination of the wafer. The gas is delivered through a hollow drive shaft and into a multi-armed susceptor support underneath the susceptor. The susceptor support arms are hollow and conduct the sweep gas from the drive shaft to the gas passages in the segmented susceptor. The gas passages within the segmented susceptor are arranged to provide even heat distribution from the sweep gas prior to delivery underneath the wafer. Short purge channels may be provided to deliver some of the sweep gas to regions surrounding the spacers to cause a continuous flow of protective purge gas around the spacers. A common bottom section may cooperate with a plurality of different top sections to form segmented susceptors suitable for supporting various sized wafers.

Claims

1. An apparatus for processing semiconductor wafers at elevated temperatures comprising:

a susceptor formed of at least two independent sections to be positioned in a high temperature processing chamber for supporting a wafer to be processed;

said susceptor including a substantially disc-shaped lower section and a substantially disc-shaped upper section having a lower surface in engagement with an upper surface of said lower section;

the engaging surfaces of said sections defining one or more gas channels therebetween;

a plurality of gas inlets in said lower section opening to its lower surface and said channels;

one or more gas outlets in said upper section opening to the upper surface of said upper section in an area beneath that in which a wafer to be processed is to be positioned, said outlets being open to said channels and thus connected to said inlets;

whereby when a wafer is placed on the susceptor and a gas is supplied through said plurality of gas inlets to said one or more gas channels and out said one or more gas outlets a flow of gas is provided under the water and out around the outer edge of the wafer; and

a shaft in communication with the susceptor for rotating said shaft together with said susceptor.

2. The apparatus of claim 1, wherein one of said sections has an outer diameter larger than that of the other section, said larger section having a recess in which the other section is positioned.

3. The apparatus of claim 2, wherein said recess is formed in a lower surface of said upper section.

4. The apparatus of claim 1, wherein said channels are formed by grooves in the side of one of the sections facing the other section, with said grooves being closed by the other section.

5. The apparatus of claim 1, wherein there are three of said inlets each opening to said channels, said channels being interconnected to allow gas flow throughout.

6. The apparatus of claim 1, wherein said outlets are located in a central portion of said upper section and said inlets are located radially outward from the outlets, said channels having a length longer than the shortest possible distance extending between any of said inlets and said outlets.

7. The apparatus of claim 1, including a plurality of spacers which stably support the wafer to be processed protruding above the upper surface of said upper section to support a wafer slightly spaced from the upper section.

8. The apparatus of claim 7, including a recess in the upper surface of said upper section with a depth greater than the height of said spacers protruding above said upper surface so that the wafer to be positioned thereon fits within said upper recess and does not project substantially above a top surface of said susceptor.

9. The apparatus of claim 7, wherein said spacers have rounded upper ends to engage the lower surface of a wafer, with only minimal contact with the wafer.

10. The apparatus of claim 7, including apertures in said upper section for receiving and retaining said spacers, said apertures being sized slightly larger than said spacers to provide some clearance therebetween, and wherein some of said channels are at least partially defined by grooves in the lower surface of said upper section closed by the upper surface of said lower section, the grooves leading to said apertures to allow gas flow around said spacers.

11. The apparatus of claim 1, wherein there are at least three of said gas inlets in said lower section, with said gas inlets being symmetrically spaced around a center of the susceptor, and said gas inlets being adapted to receive tubular arms which support the susceptor and conducts gas into said inlets.

12. The apparatus of claim 1, including a support having at least three spaced arms having upper ends which engage said gas inlets, said arms being tubular so as to be able to conduct gas to said gas inlets.

13. The apparatus of claim 1, wherein said disc-shaped lower section and said disc-shaped upper section have engaging portions to prevent relative rotation therebetween.

14. An apparatus for processing a semiconductor wafer at an elevated temperature comprising:

a substantially disc-shaped susceptor having gas channels formed therein with one or more gas inlets to said channels, said susceptor comprising two independent mating sections, with said channels being formed in the surface of one of said sections and enclosed by the other of said sections, said inlets open to a lower surface of said susceptor, said gas channels communicating with a plurality of gas outlets open to an upper surface of said susceptor; and

a support for said susceptor including a central shaft and a plurality of support arms extending radially and upwardly from said shaft with the arms having upper ends adapted to engage the lower surface of said susceptor to support the susceptor, one or more of said arms being tubular so that gas may be conducted through said tubular arms into said inlets.

15. The apparatus of claim 14, wherein the upper ends of said support arms drivingly engage the lower surface of the susceptor so that rotation of the said shaft rotates said susceptor.

16. The apparatus of claim 14, wherein said gas inlets are located spaced outwardly from the center of the susceptor, and said gas outlets are located spaced radially outwardly from the center of the susceptor and radially inward from said gas inlets, and wherein said channels extend nonlinearly between said inlets and said outlets.

17. The apparatus of claim 16, wherein said channels extend outwardly from said inlets, continue circumferentially adjacent the periphery of the susceptor lower section and finally are directed radially inwardly to said gas outlets.

18. The apparatus of claim 14, wherein said mating sections comprise a substantially disc-shaped lower section and a substantially disc-shaped upper section having a lower surface in engagement with an upper surface of said lower section, said apparatus comprising:

a plurality of spacers extending upwardly from the upper surface of said susceptor to support a wafer slightly spaced from the susceptor to permit gas from said outlets to flow beneath the wafer.

19. The apparatus of claim 18, comprising apertures in said upper section for receiving and retaining said spacers, said apertures being sized slightly larger than said spacers to provide some clearance therebetween, wherein some of said channels are formed in the lower surface of said upper section and lead to said apertures to allow gas flow around said spacers, and wherein some of said channels are formed by grooves in the upper surface of said lower section with said grooves being closed by the lower surface of said upper section the grooves leading to said outlets.

20. The apparatus of claim 18, wherein said susceptor upper surface has a shallow recess with a depth greater than the height of said spacers so that the wafer to be positioned thereon fits within said upper recess and does not project substantially above a top surface of said susceptor.

21. The apparatus of claim 14, including a plurality of spacers extending upwardly from the upper surface of said susceptor to support a wafer slightly spaced from the susceptor to permit gas from said outlets to flow beneath the wafer.

22. The apparatus of claim 21, including apertures in said susceptor for receiving and retaining said spacers, said apertures being sized slightly larger than said spacers to provide some clearance therebetween, and wherein some of said channels are in communication with said apertures to allow gas flow around said spacers.

23. An apparatus for supporting wafers in a semiconductor processing environment, comprising:

a disc-shaped lower section; and

a plurality of disc-shaped upper sections each adapted to register concentrically with said lower section, said upper sections each having an upper surface defining a shallow wafer recess sized differently than said other upper sections to enable selection of said upper section depending on the size of wafer to be processed, said upper sections each having substantially identical lower surfaces with lower recesses therein to receive an upper surface of said lower section wherein gas passages are defined between the surfaces for communicating gas from a lower surface of said lower section to said shallow wafer recess.

24. The apparatus of claim 23, wherein said lower section includes a plurality of cavities in a bottom surface for receiving arms of a susceptor support.

25. The apparatus of claim 23, including at least two upper sections for processing wafers having diameters greater than 100 mm.

26. The apparatus of claim 25, including an upper section for processing a wafer having a diameter of 100 mm.

27. The apparatus of claim 23, including a plurality of spacers adapted to fit within apertures in said upper sections and project into said recess for supporting wafers over said susceptor.

28. The apparatus of claim 27, wherein said gas passages are in communication with said spacers apertures for introducing sweep gas around said spacers and between said susceptor and said wafers.

29. An apparatus for processing a semiconductor wafers at an elevated temperature comprising:

a substantially disc-shaped susceptor having one or more gas inlets;

a plurality of spacers extending upwardly from an upper surface of said susceptor to support a wafer slightly spaced from the susceptor and permit gas to flow beneath the wafer;

generally horizontal channels formed between independent mating sections of said susceptor, said horizontal channels communicating gas from said inlets to regions above said susceptor; and

a plurality of quartz arms supporting said susceptor spaced above a chamber floor.

30. The apparatus of claim 29, wherein said spacers are made of a different material than said susceptor.

31. The apparatus of claim 30, wherein said spacers are made of sapphire.

32. The apparatus of claim 30, wherein said spacers are made of a high temperature resistant material and coated with Si, SiO₂, or SiN₃.

33. An apparatus for processing a semiconductor wafers at an elevated temperature comprising:

a substantially disc-shaped susceptor having a recess in a top surface for receiving wafers to be processed

gas channels formed in said susceptor with a plurality of gas inlets in said susceptor to said channels, and one or more gas outlets open to said recess, wherein said gas inlets and said gas outlets are located spaced radially outwardly from the center of the susceptor, said gas outlets being located radially inward from said gas inlets, and wherein said channels extend nonlinearly between said inlets and said outlets.

34. An apparatus for processing semiconductor wafers at elevated temperatures comprising:

a susceptor to be rotatably positioned in a high temperature processing chamber for supporting a wafer to be processed;

said susceptor including first and second sections, the first section having an outer diameter larger than that of the second section, and said first section having a recess in which the second section is positioned, said sections when assembled being rotationally locked with respect to each other;

one or more gas channels defined by engaging surfaces of said sections;

one or more gas inlets in said second section opening to its lower surface and said channels; and

one or more gas outlets in said first section opening to said channels and to the upper surface of said first section.