Electrostatic chuck having improved gas conduits

• US 6,108,189 A
• Filed: 11/06/1997
• Issued: 08/22/2000
• Est. Priority Date: 04/26/1996
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Maydan, Dan, Collins, Kenneth S., Lue, Brian, Kumar, Ananda H., Kholodenko, Arnold, Steger, Robert J., Grimard, Dennis S., Kats, Semyon L., Dyer, Timothy, Donde, Arik, Shamouilian, Shamouil, Narendrnath, Kadthala R., Weldon, Edwin C., Veytser, Alexander M.
• Primary Examiner(s): Sherry, Michael J.
• Application Number:
  US08/965,690
• Time in Patent Office: 1,020 Days
• Field of Search: 361/230-235, 279/128
• US Class Current: 361/234
• CPC Class Codes: C23C 16/4586 Elements in the interior of the support, e.g. electrodes, heating or cooling devices
• CPC Class Codes: H01J 2237/2001 Maintaining constant desired temperature
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks
• CPC Class Codes: Y10T 279/23 with magnetic or electrostatic means

Abstract

An electrostatic chuck 100 useful for holding a substrate 55 in a high density plasma, comprises a dielectric covered electrode 110 having at least one heat transfer gas flow conduit 150 therein. An electrical isolator 200 comprising dielectric material is positioned in the gas flow conduit 150 to (i) electrically isolate the gas in the conduit from the plasma or electrode 110, and (ii) allow passage of heat transfer gas through the conduit. Preferably, the dielectric material comprises a plasma-deactivating material that has a high surface area that reduces plasma formation of gas passing through the conduit 150 in a plasma process. A semiconducting dielectric member 115 useful for rapidly charging and discharging electrostatic chucks is also described.

Claims

1. An electrostatic chuck capable of holding a substrate in a plasma, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate;

(b) a conduit extending through one or more of the dielectric member and electrode, the conduit capable of providing gas to the surface of the dielectric member; and

(c) an electrical isolator in the conduit and at least partially within or abutting the dielectric member, the electrical isolator adapted to reduce plasma formation in and around the conduit, without blocking the passage of gas through the conduit.

2. The electrostatic chuck of claim 1 wherein the electrical isolator comprises a coating of dielectric material on a sidewall of the conduit.

3. The electrostatic chuck of claim 1 wherein the electrical isolator comprises a preformed insert in the conduit, the insert having at least one continuous passageway that allows gas to flow through the insert.

4. The electrostatic chuck of claim 1 wherein the electrical isolator comprises a porous plug of dielectric material in the conduit.

5. The electrostatic chuck of claim 1 wherein the electrical isolator comprises a plasma-deactivating material capable of reducing plasma formation in the conduit.

6. The electrostatic chuck of claim 5 wherein the plasma-deactivating material comprises continuous pore passageways that allow gas to flow through the material.

7. The electrostatic chuck of claim 1 wherein the electrical isolator comprises aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

8. The electrostatic chuck of claim 7 wherein the electrical isolator comprises a dielectric material having a resistivity of from about 10¹¹ to about 10²⁰ Ω

cm.

9. The electrostatic chuck of claim 1 wherein the dielectric member comprises a unitary body of dielectric material, and wherein the electrode is embedded in the unitary body.

10. The electrostatic chuck of claim 1 wherein the dielectric member comprises a coating of dielectric material covering the electrode.

11. An electrostatic chuck capable of holding a substrate in a plasma environment, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting a substrate;

(b) a gas conduit extending through one or more of the dielectric member or electrode, the gas conduit capable of providing gas to the surface of the dielectric member; and

(c) a plasma-deactivating material in the gas conduit and at least partially within or abutting the dielectric member, the plasma-deactivating material capable of reducing plasma formation in or near the conduit.

12. The electrostatic chuck of claim 11 wherein the plasma-deactivating material comprises at least one of the following characteristics:

(i) continuous pore passageways extending therethrough, (ii) a surface area per gram of at least about 20 cm² /gm, or (iii) a volume percent porosity of at least about 10%.

13. The electrostatic chuck of claim 11 wherein the plasma-deactivating material is made from a material selected from the group consisting of aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, and mixtures thereof.

14. The electrostatic chuck of claim 11 wherein the gas conduit comprises an outlet having non-vertical surfaces that enhance adhesion of the plasma deactivating material.

15. An electrostatic chuck capable of electrically isolating a gas flow conduit in the electrostatic chuck from a plasma environment, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the electrode; and

(b) a plasma-deactivating plug in the gas flow conduit and at least partially in or abutting the dielectric member, the plasma-deactivating plug comprising a continuous passageway that allows gas to flow therethrough and a surface area per gram of at least about 20 cm² /gm.

16. The electrostatic chuck of claim 15 wherein the passageway extends through dielectric material composed of aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

17. The electrostatic chuck of claim 15 wherein the plasma-deactivating plug comprises dielectric material shaped and sized to fit the gas flow conduit of the electrostatic chuck.

18. An electrostatic chuck capable of holding a substrate in a plasma in a process chamber, the chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate;

(b) a heat transfer gas flow conduit extending through one or more of the dielectric member and electrode, the conduit comprising an inlet capable of receiving heat transfer gas from a heat transfer gas supply, and an outlet capable of providing the heat transfer gas to the surface of the dielectric member, the outlet having a sidewall; and

(c) a plasma-deactivating coating on a portion of the sidewall of the outlet of the gas flow conduit and at least partially within or abutting the dielectric member, the plasma deactivating coating capable of reducing plasma formation in the conduit without blocking the passage of heat transfer gas through the conduit.

19. An electrostatic chuck capable of holding a substrate in a plasma in a process chamber, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate,

(b) a heat transfer gas conduit extending through one or more of the dielectric member and electrode, the conduit comprising an inlet capable of receiving heat transfer gas from a heat transfer gas supply, and an outlet capable of delivering the heat transfer gas to the surface of the dielectric member; and

(c) a preformed plasma-deactivating insert in the outlet of the gas flow conduit and at least partially within or abutting the dielectric member, the insert capable of reducing plasma formation in the conduit without blocking the passage of heat transfer gas through the conduit.

20. An electrostatic chuck capable of holding a substrate in a process chamber, the chuck comprising a dielectric covering an electrode, the dielectric having a conduit extending therethrough, and a porous material in the conduit and at least partially within or abutting the dielectric, the porous material having pores that allow passage of gas therethrough.

21. The electrostatic chuck of claim 20 wherein the porous material is shaped as a plug, and the plug is positioned at an outlet of the conduit.

22. The electrostatic chuck of claim 20 wherein the porous material comprises a hole adapted to pass gas therethrough.

23. The electrostatic chuck of claim 20 wherein the porous material comprises aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

24. The electrostatic chuck of claim 20 wherein the gas flow conduit of the electrostatic chuck comprises an outlet having a tapered region, and wherein the porous material is shaped to fill the tapered region.

25. The electrostatic chuck of claim 20 wherein the plasma-deactivating material comprises at least one of the following characteristics:

(i) continuous pore passageways extending therethrough, (ii) a surface area per gram of at least about 20 cm² /gm, or (iii) a volume percent porosity of at least about 10%.

26. An electrostatic chuck capable of holding a substrate in a plasma environment, the electrostatic chuck comprising:

(a) an electrically conductive base;

(b) a thermal-sprayed dielectric member on the base, the dielectric member having a surface capable of supporting the substrate;

(c) a heat transfer gas conduit extending through the base to provide heat transfer gas to the surface of the dielectric member, the conduit comprising an outlet having a non-vertical surface, and

(d) a plasma-deactivating material in the gas conduit and at least partially within or abutting the dielectric member.

27. The electrostatic chuck of claim 26 wherein the non-vertical surface is at an angle relative to the plane of the surface of the dielectric member to provide increased adhesion of the dielectric member onto the base.

28. The electrostatic chuck of claim 27 wherein the non-vertical surface of the outlet is tapered at an angle of at least about 15°

relative to the plane of the surface of the dielectric member.

29. The electrostatic chuck of claim 26 wherein the plasma-deactivating material is in the outlet of the conduit and is adapted to reduce plasma formation in the conduit in the plasma environment.

30. The electrostatic chuck of claim 26 wherein the plasma-deactivating material comprises at least one of:

(i) a surface area per gram of at least about 20 cm² /gm;

(ii) a volume percent porosity of at least about 10%;

or

(iii) a continuous pore passageway extending therethrough.

31. The electrostatic chuck of claim 26 wherein the plasma-deactivating material comprises a porous ceramic material.

32. A method of forming an electrostatic chuck capable of holding a substrate in a plasma, the method comprising the steps of:

(a) forming a gas flow conduit that extends through a dielectric member covering an electrode, the conduit comprising an inlet capable of receiving gas from a gas supply, and an outlet capable of delivering the gas to a surface of the dielectric member; and

(b) forming an electrical isolator in the outlet of the gas flow conduit and at least partially within or abutting the dielectric member to electrically isolate gas passing through the outlet from a plasma, without blocking the passage of gas through the conduit.

33. The method of claim 32 wherein step (b) comprises at least one of the following steps:

(i) coating a dielectric material on sidewalls of the gas flow conduit, (ii) positioning a preformed insert in the gas flow conduit, the insert having at least one continuous passageway that allows gas to flow therethrough, or (iii) forming a porous plug of dielectric material in the gas flow conduit.

34. The method of claim 32 wherein the dielectric member comprises a unitary body of semiconducting dielectric material, and wherein the electrode is embedded in the unitary body.

35. An electrostatic chuck capable of holding a substrate in a plasma process chamber, the electrostatic chuck comprising:

(a) an electrode;

(b) a dielectric member on the electrode, the dielectric member having a surface capable of supporting the substrate;

(c) a gas flow conduit extending through the electrode and dielectric member, the conduit comprising (i) an inlet capable of receiving gas from a gas supply, and (ii) an outlet capable of delivering the gas to the surface of the dielectric member; and

(d) an electrical isolator in the outlet of the gas flow conduit and at least partially within or abutting the dielectric member, the electrical isolator capable of electrically isolating the outlet of the conduit from the electrode without blocking the passage of gas through the conduit, the electrical isolator comprising one or more of (i) a dielectric coating on sidewalls of the gas flow conduit, (ii) a preformed insert sized to fit in the gas flow conduit, or (iii) a porous plug substantially filling the outlet of the gas flow conduit, the plug having a continuous passageway that allows gas to flow through the plug.

36. The electrostatic chuck of claim 35 wherein the electrical isolator comprises a plasma-deactivating material capable of reducing plasma formation in the conduit.

37. The electrostatic chuck of claim 36 wherein the plasma-deactivating material comprises a pore that allows gas to flow therethrough.

38. An electrostatic chuck capable of holding a substrate in a plasma, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate;

(b) a gas flow passageway extending through one or more of the dielectric member and electrode, the passageway comprising a dimension within or adjacent to the dielectric member sufficiently small to preclude plasma formation therein.

39. The electrostatic chuck of claim 38 wherein the gas flow passageway comprises an outlet capable of delivering gas to the surface of the dielectric member, the outlet having a diameter equal to or less than about 0.4 mm.

40. The electrostatic chuck of claim 39 wherein the diameter of the outlet is equal to or less than about 0.25 mm.

41. The electrostatic chuck of claim 38 wherein the gas flow passageway is formed in an insert positioned in a conduit in the dielectric member or electrode.

42. The electrostatic chuck of claim 41 wherein the dielectric member comprises aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

43. An electrostatic chuck capable of holding a substrate in a plasma, the chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate;

(b) a conduit extending through one or more of the dielectric member and electrode; and

(c) a tubular insert in the conduit and at least partially within or abutting the dielectric member, the tubular insert having a gas flow passageway with a diameter sufficiently small to substantially preclude plasma formation in the passageway.

44. The electrostatic chuck of claim 43 wherein the gas flow passageway comprises an outlet capable of delivering gas to the surface of the dielectric member, the outlet having a diameter equal to or less than about 0.4 mm.

45. The electrostatic chuck of claim 44 wherein the outlet comprises a diameter that is equal to or less than about 0.25 mm.

46. The electrostatic chuck of claim 43 wherein the tubular insert comprises an outwardly extending ledge sized sufficiently large to hold the tubular insert in the conduit.

47. The electrostatic chuck of claim 46 wherein the thickness of the ledge is selected to hold the electrostatic chuck at a predetermined distance from a metal base during bonding of the electrostatic chuck to the metal base.

48. The electrostatic chuck of claim 43 wherein the dielectric member comprises aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

49. An electrostatic chuck capable of holding a substrate in a plasma, the electrostatic chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate, and having a gas flow conduit extending therethrough; and

(b) an electrical isolator in the gas flow conduit and at least partially within or abutting the dielectric member, the electrical isolator adapted to electrically isolate the gas in the conduit from the plasma without blocking the passage of gas through the conduit, the electrical isolator comprising an electrical lead therein.

50. The electrostatic chuck of claim 49 wherein the electrical lead of the electrical isolator is electrically connected to a ground potential.

51. The electrostatic chuck of claim 49 wherein the electrical lead of the electrical isolator is electrically connected to a conductor below the chuck.

52. The electrostatic chuck of claim 49 wherein the electrical isolator comprises a preformed insert having a continuous passageway that allows gas to flow therethrough, and wherein the electrical lead is embedded in the preformed insert.

53. The electrostatic chuck of claim 49 wherein the electrical isolator comprises a porous dielectric material composed of aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

54. The electrostatic chuck of claim 53 wherein the electrical isolator comprises a dielectric material having a resistivity of from about 10¹¹ to about 10²⁰ Ω

cm.

55. An electrostatic chuck capable of holding a substrate in a plasma, the chuck comprising:

(a) a dielectric member covering an electrode, the dielectric member having a surface capable of supporting the substrate, and having a gas flow conduit extending therethrough; and

(b) an electrical isolator in the gas flow conduit and at least partially within or abutting the dielectric member, the electrical isolator adapted to electrically isolate the gas in the conduit from the plasma, the electrical isolator comprising an opening around the electrical isolator, the opening sized to allow passage of gas therethrough while reducing plasma formation in and adjacent to the opening.

56. The electrostatic chuck of claim 55 wherein the electrical isolator comprises a ceramic insert surrounded by a polymer sleeve.

57. The electrostatic chuck of claim 55 wherein the polymer sleeve comprises tetrafluoroethylene or silicone.

58. The electrostatic chuck of claim 55 wherein the electrical isolator further comprises an electrical lead that is electrically connected to a conductor below the chuck.

59. The electrostatic chuck of claim 55 wherein the electrical isolator comprises a porous dielectric material composed of aluminum oxide, aluminum nitride, titanium oxide, silicon dioxide, zirconium oxide, silicon carbide, silicon nitride, or mixtures thereof.

60. The electrostatic chuck of claim 55 wherein the electrical isolator comprises a dielectric material having a resistivity of from about 10¹¹ to about 10²⁰ Ω

cm.

61. A method of forming an electrostatic chuck, the method comprising the steps of:

(a) forming an electrode having an upper surface, and a conduit extending therethrough;

(b) forming an electrical isolator in the conduit and abutting the upper surface, the electrical isolator comprising a continuous passageway to allow passage of heat transfer gas through the conduit; and

(c) forming a dielectric member covering the upper surface of the electrode to expose the passageway in the electrical isolator.

62. The method of claim 61 wherein step (b) comprises the steps of:

(i) inserting a masking pin into the conduit in the electrode;

(ii) forming the electrical isolator by depositing dielectric material on a surface of the conduit surrounding the masking pin; and

(iii) removing the masking pin from the conduit.

63. The method of claim 61 wherein step (b) comprises the steps of:

(i) fabricating an electrical isolator sized to fit in the conduit of the electrode;

(ii) inserting the electrical isolator into the conduit so that an apex of the electrical isolator extends out of the electrode; and

(iii) removing the apex of the electrical isolator by a method selected from the group consisting of grinding and ablating.

64. The method of claim 61 wherein step (c) comprises the steps of:

(i) forming a semiconducting dielectric member on the upper surface of the electrode so that the semiconducting dielectric member substantially covers the electrical isolator; and

(ii) removing a surface of the semiconducting dielectric member until the passageway in the electrical isolator is exposed.