Uniform gas distribution in large area plasma source

• US 6,682,630 B1
• Filed: 03/29/2002
• Issued: 01/27/2004
• Est. Priority Date: 09/29/1999
• Status: Expired due to Fees

• Current Assignee: European Community
• Original Assignee: European Community
• Inventors: Rossi, François, Colpo, Pascal
• Primary Examiner(s): ALEJANDRO MULERO, LUZ L
• Application Number:
  US10/088,512
• Time in Patent Office: 669 Days
• Field of Search: 118/723.I, 118/723.IR, 118/723.AN, 118/715, 118/723.R, 118/723.E, 118/723.MR, 118/723.MA, 156/345.48, 156/345.49, 156/345.47, 156/345.33, 156/345.34, 156/345.42, 156/345.46, 204/298.07, 204/298.16, 204/298.33, 204/298.37, 315/111.51
• US Class Current: 156/345.48
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means

Abstract

An apparatus configured to generate a time-varying magnetic field through a field admission window of a plasma processing chamber to create or sustain a plasma within the chamber by inductive coupling. The apparatus includes a magnetic core presenting a pole face structure,—an inductor means associated with the magnetic core, arranged to generate a time-varying magnetic field through the pole face structure, and—a device for injecting gas into the chamber and through the chamber and through the magnetic core.

Claims

1. An apparatus for generating a time-varying, magnetic field in a plasma processing chamber (20) to create or sustain a plasma within the chamber by inductive coupling, comprising:

a magnetic core (38;

138) presenting a pole face (38a;

39a)

an inductor (40) associated with the magnetic core arranged to generate a time-varying magnetic field throughout the pole face,

injector apparatus (42,43,44,45,48,49,51,91,93,95,142,144) arranged to inject gas into said chamber (20) and through said magnetic core.

2. The apparatus according to claim 1, wherein said injector apparatus forms a showerhead-like gas injection (52, 54).

3. The apparatus according to claim 1 wherein said injector apparatus comprises a plurality of injection pipes (42, 43, 44, 45,142, 144) distributed or disposed through the magnetic core.

4. The apparatus according to claim 3, wherein said pipes are connected to gas distributing apparatus (48, 48a, 48b, 49, 51, 91, 93, 95) arranged to distribute gas to the injection pipes.

5. The apparatus according to claim 4, said gas distributing apparatus being located on the side of the magnetic core opposite to an inner space (50) of said plasma processing chamber (20).

6. The apparatus according to claim 4, said gas distributing apparatus comprising a common gas distributing pipe (48, 48a, 48b, 49), through which gas is distributed to the injection pipes.

7. The apparatus according to claim 4, said gas distributing apparatus comprising a cover (91), located on the side of the magnetic core opposite to an inner space (50) of said plasma processing chamber (20), with a gap (93) between said cover and said magnetic core, said injection pipes (42, 44) being open in said gap.

8. The apparatus according to claim 3, said injection pipes being made of a material selected from the group consisting of stainless steel and an insulating material.

9. The apparatus according to claim 3, said injection pipes having different diameters from each other.

10. A plasma processing apparatus comprising:

a plasma processing chamber (20) having at least one field admission window (122, 122a, 122b),

at least one magnetic field generating apparatus according to claim 3, arranged to create a time-varying magnetic field in the chamber by inductive coupling through a corresponding field admission window, each of said injection pipes traversing said window through a corresponding hole in said window, and an end of each of said injection pipes being welded to the periphery of said corresponding hole,

a power source (60) arranged to drive the magnetic field generating apparatus.

11. The apparatus according to claim 10, further comprising a workpiece support (38, 40;

142) adapted to hold at least one workpiece (26) at portions outside surfaces of the workpiece(s) to be exposed to an energy field from the two or more field admission windows (122a, 122b).

12. The apparatus according to claim 11, wherein the workpiece support (38, 40;

142) is adapted to hold at least one workpiece (26) at edge portions thereof.

13. The apparatus according to claim 1, said pole face (38a) being curved.

14. The apparatus according to claim 1, wherein the pole face (38) is constituted by a single pole face (38a) of unitary construction.

15. The apparatus according to claim 1, wherein the pole face (38) is divided into two or more pole faces that confront respective portions of the plasma processing chamber.

16. The apparatus according to claim 15, wherein the divided pole faces are associated to respective inductors and power supplies whilst being kept in phase to ensure that all the pole faces have the same polarity at any one time.

17. The apparatus according to claim 15, wherein the divided pole faces physically depend from a common magnetic core and inductor.

18. The apparatus according to claim 1, wherein the pole face (38a) constitutes an end face of the magnetic core (38).

19. The apparatus according to claim 1, wherein the magnetic core comprises at least one discontinuity (37) so as to prevent the circulation of eddy currents around the core.

20. The apparatus according to claim 19, wherein the discontinuity is in the form of one or more laminations (37).

21. The apparatus according to claim 20, wherein the lamination(s) (37) extend(s) radially from a point proximal to or at the centre of the core (38) to the periphery of the core.

22. The apparatus according to claim 1, wherein said core (38) has a unitary structure.

23. The apparatus according to claim 1, wherein the inductor (40) comprises a conductor arranged to form one or more turns around at least a portion of the magnetic core (38).

24. The apparatus according to claim 1, wherein the inductor (40) is wound around the periphery of the magnetic core (38).

25. The apparatus according to claim 1, wherein the inductor (40) comprises a planar winding recessed within a groove (47) or groove pattern (46) formed in the magnetic core, on the pole face (38a;

39a).

26. The apparatus according to claim 1, wherein the inductor (40) is driven by a power supply (61) delivering power at a frequency of around 10 kHz to 100 MHz, preferably at a frequency of 13.56 MHz.

27. The apparatus according to claim 1, further comprising biasing apparatus arranged to bias the core with at least one bias selected from the group consisting of:

an ac bias (including radio frequencies), a dc bias, and a ground bias.

28. The apparatus according to claim 1, further comprising cooling apparatus arranged to cool the core (26).

29. A plasma processing apparatus comprising:

a plasma processing chamber (20) having at least one field admission opening (94a, 94b),

at least one magnetic field generating apparatus according to claim 1, arranged to create a time-varying magnetic field in the chamber,

a power source arranged to drive the magnetic field generating apparatus.

30. The apparatus according to claim 29, further comprising a barrier (80, 80a;

80b) formed between a field emission surface and the plasma environment arranged so as to prevent that surface from contaminating the chamber (20).

31. The apparatus according to claim 30, said barrier comprising a sheet of dielectric material (80, 80a, 80b) maintained between said pole face structure and an inner space of said plasma processing chamber(20).

32. The apparatus according to claim 31, a distance between said sheet of dielectric material and said face structure being less than 1 mm.

33. The apparatus according to claim 30, wherein the barrier (80) is mounted without contacting a field emission face of the magnetic field generating apparatus, the barrier being held at one of the periphery of the field emission face and the process chamber (20).

34. The apparatus according to claim 33 wherein a pressure adjuster is provided to balance the pressure conditions between the inner and outer faces of the barrier (80).

35. The apparatus according to claim 34, wherein the pressure adjuster comprises a valve arrangement arranged and operative to allow the pressure at the outer face of the barrier (80) to follow that of the process chamber (20) when the latter is submitted to changing pressure conditions, for example, during vacuum pumping or gas admission, or setting to atmospheric pressure for loading and unloading a workpiece, and to seal off the space above the outer surface of surface of the barrier when the chamber is operative for plasma processing such that no contaminant from the energy field generator can reach the plasma environment of the process chamber.

36. The Apparatus according to claim 29, said magnetic core or said pole face having an active field emission area whose size and shape matches or substantially matches the field admission opening or the field admission window.

37. The apparatus according to claim 29, one of said magnetic core and said pole face having an active field emission area whose size and shape is smaller than an area of the field admission opening or the field admission window.

38. The apparatus according to claim 29, further comprising at least one field admission window (122) between an inner space (50) of said plasma chamber and said magnetic field generating apparatus.

39. The apparatus according to claim 38, said magnetic core presenting a face being adapted to be applied against or in proximity to the window (122).

40. The apparatus according to claim 38, said inductive type plasma processing chamber (20) having two or more windows (122a, 122b) for receiving induced field energy, each window enabling induced field energy to enter the chamber from a respective direction.

41. The apparatus according to claim 40, provided with at least one pair of oppositely-facing windows (122a, 122b).

42. The apparatus according to claim 38, further comprising one or more partitions to isolate spaces therein associated with one or a group of windows (122a, 122b).

43. The apparatus according to claim 38, wherein the windows (122a, 122b) are non planar to follow a contour of a wall portion from which they depend.

44. A plasma processing apparatus comprising:

a plasma processing chamber (20) having at least one field admission window (122),

at least one magnetic field generating apparatus according to claim 1, arranged to create a time-varying magnetic field in the chamber by inductive coupling through a corresponding field admission window, said injector apparatus and through said magnetic core traversing said window,

a power source (61) arranged to drive the magnetic field generating apparatus.

45. Use of a plasma processing chamber according to claim 1 for processing a workpiece (16).