High temperature ceramic heater assembly with RF capability and related methods

• US 5,968,379 A
• Filed: 02/12/1997
• Issued: 10/19/1999
• Est. Priority Date: 07/14/1995
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated, BAE Systems Advanced Ceramics, Inc. (Trelleborg AB)
• Original Assignee: Applied Materials Incorporated
• Inventors: Palicka, Richard, Zhao, Jun, Wolff, Stefan, Sajoto, Talex, Luo, Lee, Dornfest, Charles, Selyutin, Leonid, Mortensen, Harold
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US08/800,096
• Time in Patent Office: 979 Days
• Field of Search: 219/121.4, 219/121.43, 219/121.44, 219/121.58, 219/121.52, 219/158-160, 156/345, 156/646.1, 204/288.12, 204/298.37, 204/298.38, 118/723 ME, 118/723 I, 118/725, 118/724
• US Class Current: 219/121.52
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: C23C 16/4586 Elements in the interior of the support, e.g. electrodes, heating or cooling devices
• CPC Class Codes: C23C 16/5096 Flat-bed apparatus
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: H01L 21/67103 mainly by conduction
• CPC Class Codes: H01L 21/68785 characterised by the mechanical construction of the susceptor, stage or support
• CPC Class Codes: H01L 21/68792 characterised by the construction of the shaft

Abstract

The present invention provides systems, methods and apparatus for depositing titanium films at rates up to 200 Å/minute on semiconductor substrates from a titanium tetrachloride source. In accordance with an embodiment of the invention, a ceramic heater assembly with an integrated RF plane for bottom powered RF capability allows PECVD deposition at a temperature of at least 400° C. for more efficient plasma treatment. A thermal choke isolates the heater from its support shaft, reducing the thermal gradient across the heater to reduce the risk of breakage and improving temperature uniformity of the heater. A deposition system incorporates a flow restrictor ring and other features that allow a 15 liters/minute flow rate through the chamber with minimal backside deposition and minimized deposition on the bottom of the chamber, thereby reducing the frequency of chamber cleanings, and reducing clean time and seasoning. Deposition and clean processes are also further embodiments of the present invention.

Claims

1. A heater assembly suitable for use in semiconductor wafer fabrication, said heater assembly comprising:

an RF electrode;

a heater element;

a ceramic heater pedestal including a ceramic body and a ceramic flange connected to said ceramic body, said ceramic body having a top surface for supporting a substrate, said ceramic flange having a bottom surface, said RF electrode disposed in said ceramic body at a first distance below said top surface, and said heater element disposed in said ceramic body at a second distance below said RF electrode, said ceramic flange having formed therein a first recess, a second recess and a third recess;

a first conductor coupled to said RF electrode, said first conductor disposed through said first recess; and

a second conductor coupled to said heater electrode and a third conductor coupled to said heater electrode, said second and third conductors disposed through said second and third recesses.

2. The heater assembly of claim 1 wherein said ceramic body and said ceramic flange are comprised of aluminum nitride.

3. The heater assembly of claim 1 wherein said RF electrode is comprised of molybdenum.

4. The heater assembly of claim 1 wherein said RF electrode is a perforated metal plate with a thickness between about 3-15 mil.

5. The heater assembly of claim 4 wherein said perforated metal plate has a thickness between about 3-6 mil.

6. The heater assembly of claim 1 wherein said first distance is less than about 200 mil.

7. The heater assembly of claim 6 wherein said first distance is less than about 50 mil.

8. The heater assembly of claim 2 wherein said first distance ranges between about 38-42 mil.

9. The heater assembly of claim 1 wherein said ceramic flange is on a distal end of a ceramic stub, the ceramic stub having a length less than about 5 inches.

10. The heater assembly of claim 9 wherein the length of said ceramic stub is between about 2-5 inches.

11. The heater assembly of claim 2 wherein said first distance allows the heater assembly to be repeatedly cycled between room temperature and at least about 500°

C.

12. The heater assembly of claim 11 wherein said heater assembly is cycled in an environment including a chlorinated plasma species.

13. The heater assembly of claim 12 wherein the heater assembly is operated at a temperature of at least 620°

C.

14. The heater assembly of claim 1 wherein said heater element is a metal ribbon comprising a sinuous flat ribbon generally formed in concentric C-loops.

15. The heater assembly of claim 1 wherein said metal ribbon comprises molybdenum.

16. The heater assembly of claim 14 wherein said metal ribbon has a thickness of between about 3-8 mil.

17. A pressure-bonded ceramic assembly comprising:

a first ceramic plate;

a perforated metal plane having a plurality of perforations; and

a second ceramic plate;

wherein said perforated metal plane is disposed between said first ceramic plate and said second ceramic plate, and said first ceramic plate is bonded to said second ceramic plate through said plurality of perforations with a ceramic material, and said first ceramic plate has a thickness determined by electric field performance of said perforated metal plane when used as an RF electrode.

18. The assembly of claim 17 wherein said perforated metal plane comprises a sheet of molybdenum, said sheet having a thickness between about 3-15 mil.

19. The assembly of claim 17 wherein said first ceramic plate, said second ceramic plate, and said ceramic material comprise aluminum nitride.

20. The assembly of claim 18 further comprising:

a first molybdenum electrode, joined to said molybdenum sheet;

a nickel RF standoff rod; and

a eutectic layer disposed between said standoff rod and said first molybdenum electrode.

21. The assembly of claim 20 wherein said first molybdenum electrode comprises:

a first section with a first cross-sectional area in contact with said sheet, and a second section with a second cross-sectional area in contact with said RF standoff rod, wherein said first cross-sectional area is greater than said second cross-sectional area.

22. The assembly of claim 20 further comprising a tungsten slug disposed at an interface between said first molybdenum electrode and said RF standoff rod.

23. The assembly of claim 21 wherein said first molybdenum electrode substantially tapers from said first section out to said second section.

24. The assembly of claim 17 further comprising:

a metal ribbon heating element, said metal ribbon heating element having a pattern, said pattern providing spaces separating portions of said metal ribbon heating element; and

a third ceramic plate;

wherein said metal ribbon heating element is disposed between said second ceramic plate and said third ceramic plate, and said second ceramic plate is bonded to said third ceramic plate through said spaces in said pattern of said metal ribbon heating element.

25. The assembly of claim 24 wherein said metal ribbon heating element comprises molybdenum.

26. The assembly of claim 24 wherein said pattern is a sinuous pattern.

27. The assembly of claim 25 wherein said third ceramic plate comprises aluminum nitride.

28. The assembly of claim 27 further comprising:

a second molybdenum electrode, joined to said molybdenum metal ribbon heating element;

a nickel heater standoff rod; and

a eutectic layer disposed between said heater standoff rod and said second electrode.

29. The assembly of claim 28 wherein said second molybdenum electrode comprises:

a third section with a third cross-sectional area in contact with said heater element, and a fourth section with a fourth cross-sectional area in contact with said heater standoff rod, wherein said third cross-sectional area is greater than said fourth cross-sectional area.

30. The assembly of claim 29 further comprising a tungsten slug disposed at an interface between said second electrode and said heater standoff rod.

33. The assembly of claim 17 wherein the perforated metal plane has a perforated area of approximately 45% of a total area.

34. The assembly of claim 33, said plurality of perforations each having a diameter of approximately 45 mil on approximately 200 mil centers.

35. The assembly of claim 17 wherein said thickness of said first ceramic plate is less than about 50 mils.

31. An assembly comprising:

a first ceramic plate;

a second ceramic plate;

a planar molybdenum element disposed between and pressure bonded to said first ceramic plate and said second ceramic plate;

a molybdenum electrode coupled to said planar molybdenum element at a first end and having a second end extending at least partially through said second ceramic plate; and

a nickel electrode coupled to said second end of said molybdenum electrode with a eutectic.

32. The heater assembly of claim 31 further comprising a tungsten element proximate to said eutectic.