Plasma processing apparatus

• US 9,767,993 B2
• Filed: 10/03/2012
• Issued: 09/19/2017
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Ishibashi, Kiyotaka, Morita, Osamu
• Primary Examiner(s): DHINGRA, RAKESH KUMAR
• Application Number:
  US14/349,807
• Publication Number:
  US 20140262034A1
• Time in Patent Office: 1,812 Days
• Field of Search: 118723 MW, 118723 R, 15634541
• CPC Class Codes: C23C 16/45563 Gas nozzles
• CPC Class Codes: C23C 16/511 using microwave discharges
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32201 Generating means
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32495 Means for protecting the vessel against plasma
• CPC Class Codes: H05H 1/463 using antennas or applicators

Abstract

This microwave plasma processing apparatus has, as a gas introduction mechanism for introducing a working gas inside a chamber (10), electrical discharge prevention members (96(1) to 96(8)), each of which is provided to a plurality of dielectric window gas passages (94(1) to (94(8)) through which a dielectric window (54) passes. Each electrical discharge prevention member (96(n)), a portion (114) of which protrudes only a height h, which is greater than or equal to a predetermined distance H, upward from the rear surface of a dielectric window (52) on the inlet side, passes through an opening (54a) of a slot plate (54), and inserts into a branched gas supply path (92(n)) of a gas branch part (90). The gas branch part (90), spring coils (116) and the slot plate (54), which surround the protruding portion (114) of each electrical discharge prevention member (96(n)), constitute an enclosing conductor (118).

Claims

1. A plasma processing apparatus, comprising:

a processing container;

a substrate holding unit configured to hold a substrate in the processing container;

a coaxial waveguide and a dielectric window for introducing a microwave over the substrate holding unit;

a dielectric window gas flow path that penetrates the dielectric window;

a processing gas supply unit including an external gas supply path connected to the dielectric window gas flow path from above or a side of the dielectric window, the processing gas supply unit being configured to supply at least a part of a required processing gas into the processing container through the external gas supply path and the dielectric window gas flow path;

an electromagnetic wave supply unit configured to supply electromagnetic waves into the processing container through the dielectric window;

an electric discharge prevention member integrally formed in or coupled to the dielectric window, including an inlet connected to an outlet of the external gas supply path, and configured to form a portion or whole of the dielectric window gas flow path, an inlet side portion of the electric discharge prevention member protruding from a surface of the dielectric window by at least a predetermined distance H; and

a surrounding conductor including a connector unit, the surrounding conductor configured to surround the inlet side portion of the electric discharge prevention member, the connector unit connected to a lower end of an inner conductor of the coaxial waveguide;

wherein the predetermined distance H is determined by a wavelength of the electromagnetic waves and a size of the surrounding conductor in a radial direction, and further wherein the electric discharge prevention member is air permeable and the processing gas passes through the electric discharge prevention member.

2. The plasma processing apparatus of claim 1, wherein, assuming that a wavelength the electromagnetic waves is λ

_d when the electromagnetic waves are propagated within the electric discharge prevention member, H≧

0.05λ

_d.

3. The plasma processing apparatus of claim 2, wherein H≦

0.3λ

_d.

4. The plasma processing apparatus of claim 1, wherein, assuming that an inner diameter of the surrounding conductor or a length of a major axis of a maximum inscribed ellipse of the surrounding conductor is D, H≧

0.13D.

5. The plasma processing apparatus of claim 4, wherein H≧

0.5D.

6. The plasma processing apparatus of claim 1, wherein, assuming that the wavelength of the electromagnetic waves is λ

_d when the electromagnetic waves are propagated within the electric discharge prevention member and an inner diameter of the surrounding conductor or a length of a major axis of a maximum inscribed ellipse of the surrounding conductor is D, D≦

0.6λ

_d.

7. The plasma processing apparatus of claim 1, wherein a plurality of dielectric window gas flow paths are provided in the dielectric window in parallel to each other.

8. The plasma processing apparatus of claim 7, wherein, assuming that a distance between a center of the dielectric window and each of the dielectric window gas flow paths is R and the wavelength of the electromagnetic waves is λ

_g when the electromagnetic waves are propagated within the dielectric window, λ

_g/4<

R<

5λ

_g/8.

9. The plasma processing apparatus of claim 8, wherein no dielectric window gas flow path is provided within λ

_g/4 from the center of the dielectric window.

10. The plasma processing apparatus of claim 8, wherein the dielectric window has a rotational symmetry property.

11. The plasma processing apparatus of claim 7, wherein the plurality of dielectric window gas flow paths are arranged on a circumference of a predetermined distance from the center of the dielectric window at equidistant intervals.

12. The plasma processing apparatus of claim 1, wherein the electric discharge prevention member includes a porous dielectric material.

13. The plasma processing apparatus of claim 1, wherein the electric discharge prevention member includes a dielectric material which is formed with a plurality of extra fine through holes.

14. The plasma processing apparatus of claim 1, wherein the electric discharge prevention member includes a dielectric material which is formed with a plurality of longitudinal grooves extending in an axial direction on an outer circumferential surface thereof.

15. The plasma processing apparatus of claim 1, wherein the electric discharge prevention member includes a cylinder portion which is made of a dielectric material and integrally formed in or bonded to the dielectric window.

16. The plasma processing apparatus of claim 1, wherein the electric discharge prevention member protrudes on the rear side of the dielectric window and the protruding portion is surrounded by the surrounding conductor.

17. The plasma processing apparatus of claim 1, wherein at least a portion of the external gas supply path in the vicinity of the outlet is made of a conductor and integrally extending from or connected with the surrounding conductor.

18. The plasma processing apparatus of claim 1, wherein the surrounding conductor is segmented into a plurality of conductor members which are connected with each other along an axial direction.

19. The plasma processing apparatus of claim 1, wherein an electromagnetic field absorption member is provided between a side surface of the electric discharge prevention member and the surrounding conductor.

20. The plasma processing apparatus of claim 1, wherein an endless seal member is provided between a side surface of the electric discharge prevention member and the surrounding conductor.

21. The plasma processing apparatus of claim 20, wherein a recess shielded from an atmospheric space by the seal member is formed between the side surface of the electric discharge prevention member and the surrounding conductor, and

the surrounding conductor surrounds the side surface of the electric discharge prevention member over an extent which is equal to or longer than the predetermined distance H, from the deepest position of the recess.

22. The plasma processing apparatus of claim 1, wherein an endless seal member is provided between an end surface of the inlet of the electric discharge prevention member and the outlet of the external gas supply path.

23. The plasma processing apparatus of claim 22, wherein a gap formed inside the seal member in the vicinity of the inlet of the electric discharge prevention member is larger than a gap formed outside the seal member.

24. The plasma processing apparatus of claim 23, wherein the gap outside the seal member is 0.2 mm or less and the gap inside the seal member is 0.3 mm or more.

25. The plasma processing apparatus of claim 24, wherein the gap inside the seal member is 0.5 mm to 1.0 mm.

26. The plasma processing apparatus of claim 1, wherein an endless seal member is provided between the dielectric window and the outlet of the external gas supply path.

27. The plasma processing apparatus of claim 1, wherein the electromagnetic wave supply unit includes an antenna provided above the dielectric window so as to supply the electromagnetic waves into the processing container.

28. The plasma processing apparatus of claim 27, wherein the antenna is a flat plate-type slot antenna.

29. The plasma processing apparatus of claim 28, wherein the flat plate-type slot antenna has a rotational symmetry property.

30. The plasma processing apparatus of claim 28, wherein a slot plate in the flat plate-type slot antenna forms a part of the surrounding conductor.

31. The plasma processing apparatus of claim 28, wherein the electromagnetic wave supply unit includes:

a microwave generator configured to generate microwaves as the electromagnetic waves, and

a microwave transmission line configured to propagate the microwaves generated from the microwave generator to the flat plate-type slot antenna.

32. The plasma processing apparatus of claim 27, wherein the antenna is a coil type antenna.

33. The plasma processing apparatus of claim 32, wherein the electromagnetic wave supply unit includes:

a high frequency power source configured to generate high frequency waves as the electromagnetic waves,

a high frequency wave transmission unit configured to transmit the high frequency waves from the high frequency power source to the antenna, and

a matching unit configured to match a load impedance of the antenna side to an impedance of the high frequency power source side.

34. The plasma processing apparatus of claim 1, wherein the outlet of the electric discharge prevention member extends to an outlet of the dielectric window gas flow path which faces the plasma generation space within the processing container so as to form a gas jet port.