Plasma processing apparatus

• US 5,698,036 A
• Filed: 05/24/1996
• Issued: 12/16/1997
• Est. Priority Date: 05/26/1995
• Status: Expired due to Term

• Current Assignee: Junichi Takada, Makoto Ando, Naohisa Goto, Tokyo Electron Limited, Yasuhiro Horiike
• Original Assignee: Junichi Takada, Makoto Ando, Naohisa Goto, Tokyo Electron Limited, Yasuhiro Horike
• Inventors: Ando, Makoto, Goto, Naohisa, Horike, Yasuhiro, Takada, Junichi, Kobayashi, Yasuo, Ishii, Nobuo
• Primary Examiner(s): Tsai, Jey
• Assistant Examiner(s): CHANG, JONI YUK YING
• Application Number:
  US08/653,469
• Time in Patent Office: 571 Days
• Field of Search: 118/723 MW, 118/723 MR, 118/723 MA, 118/723 MP, 118/723 AN, 156/345, 216/69, 216/70, 204/298.38
• US Class Current: 118/723.0MW
• CPC Class Codes: C23C 16/511 using microwave discharges
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/3222 Antennas
• CPC Class Codes: H01J 37/32229 Waveguides

Abstract

A plasma processing apparatus comprises a processing container, a waveguide tube for guiding microwaves generated by a microwave generator, and a flat antenna member connected to the wave guide and disposed in the container to face a semiconductor wafer supported in the container. The antenna includes a plurality of short slits concentrically or spirally arranged in the antenna. The slits are spaced apart in the widthwise direction at intervals of 5% to 50% of a guide wavelength of the microwave, and each of the slits has a length of +30% of the guide wavelength centered with respect to half of the guide wavelength.

Claims

1. A plasma processing apparatus comprising:

a processing container;

support means disposed in said processing container, supporting a member to be processed which has a surface to be processed;

a microwave generator for generating microwaves;

a waveguide tube for guiding microwaves generated by said microwave generator into said processing container;

a flat antenna member electrically connected to said waveguide tube, facing, apart for an interval, said surface of said member to be processed, which is supported by said support means, and disposed to define a plasma forming region between said flat antenna member and said surface of said member to be processed; and

means for supplying processing gas to said plasma forming region,

said antenna member including a conductive plate and a multiplicity of slits formed in the conductive plate, the distribution and dimensions of slits being set so that an electrostatic field exponentially attenuating with the distance from said antenna member, is formed in said plasma forming region to generate plasma of said processing gas in said plasma forming region.

2. A plasma processing apparatus according to claim 1, wherein said conductive plate has a center and a peripheral portion, said slits are formed on a multiplicity of loops, the diameters of which gratualy increase from the center of said conductive plate toward the outer periphery extend along said loops, and are spaced apart from one another in both lengthwise and widthwise directions, said slits have lengths shorter than the guide wavelength of said microwaves, and the widthwise directional interval between adjacent slits is set to be shorter than said guide wavelength of said microwave.

3. A plasma processing apparatus according to claim 2, wherein each of said slits has a length of ±

30% of said guide wavelength centered with respect to half of said guide wavelength of said microwave.

4. A plasma processing apparatus according to claim 3, wherein said slits are spaced apart in the widthwise direction at intervals of 5% to 50% of the guide wavelength of said microwave.

5. A plasma processing apparatus according to claim 2, wherein said conductive plate has a metal disc and said slits are concentrically or spirally disposed in said metal disc.

6. A plasma processing apparatus according to claim 2, wherein phases of electrostatic fields formed by said slits adjacent in the radial direction of said antenna member are made to be opposite.

7. A plasma processing apparatus according to claim 2, wherein lengths of said slits are sequentially enlarged in a radial direction from the central portion of said antenna member toward the outer periphery of said antenna member, so that the density of plasma in the outer periphery of said antenna member is higher than that in the central portion of said antenna member.

8. A plasma processing apparatus according to claim 2, wherein outermost slits in said conductive plate are longer than the other slits.

9. A plasma processing apparatus according to claim 1, further comprising an insulating protective plate for covering the surface of said flat antenna member that faces said member to be processed.

10. A plasma processing apparatus according to claim 8, further comprising a dielectric member for covering a surface of said flat antenna member opposite to the surface which faces said member to be processed to shorten the wavelength of said microwaves to be supplied from the waveguide tube to make the wavelength to be the guide wavelength.

11. A plasma processing apparatus according to claim 10, wherein said protective plate, said flat antenna member and said dielectric member are formed integrally by brazing.

12. A plasma processing apparatus according to claim 1, wherein said container has an outer wall having an opening, at an interval, facing said surface of said member to be processed which is supported by said support means and a surrounding portion for surrounding said opening, and which further comprises an antenna covering member for covering and supporting said antenna member so that said flat antenna member, at an interval, faces the surface of said member to be processed supported by said support means through said opening and means for mounting said antenna covering member to said outer peripheral portion so that said opening is closed.

13. A plasma processing apparatus according to claim 12, wherein said antenna covering member has a heat radiation surface exposed to the atmosphere so as to be cooled by the atmosphere.

14. A plasma processing apparatus according to claim 13, further comprising:

a dielectric member disposed between said antenna covering member and said flat antenna member to shorten the wavelength of microwave to be supplied to said antenna member so as to make the wavelength to be the guide wavelength; and

means for integrally attaching said antenna covering member, said antenna member and said dielectric member in such a manner that gaps among said antenna covering member, said antenna member and said dielectric member are filled with the attaching means.

15. A plasma processing apparatus according to claim 14, wherein said antenna covering member, said antenna member and said dielectric member face mutually and said attaching means has a good heat conductivity.

16. A plasma processing apparatus according to claim 15, wherein said antenna covering member includes a plate-like body having one surface having a circular recess having a central axis, the other surface exposed to the atmosphere and a through hole penetrating between said two surfaces coaxially with said central axis and allowed to communicate with said recess;

said dielectric member has a disc-like body disposed coaxially in said recess and having a through hole penetrating coaxially with said central axis;

said flat antenna member is attached to said one surface of said antenna covering member and said body of said dielectric member in such a manner that said flat antenna member is disposed coaxially with said antenna covering member and said body of said dielectric member to cover said recess; and

said waveguide tube has a tubular external conductor having an end attached to the other surface of said antenna covering member and a central conductor having an end allowed to pass through said through holes of said antenna covering member and said body of said dielectric member and electrically connected to the center of said antenna member.

17. A plasma processing apparatus according to claim 16, wherein said central conductor of said waveguide tube is formed into a tubular shape having one opened end facing the central portion of said antenna member and the other opened end;

said means for supplying the processing gas has a processing gas source and a supply line for connecting said processing gas source to the other opened end of said central conductor of said waveguide tube; and

said antenna member has at least one gas passing hole formed in the central portion thereof;

whereby said processing gas is jetted out to said plasma forming region from said supply line through said central conductor and said gas passing hole.

18. A plasma processing apparatus according to claim 17, wherein said means for supplying said processing gas has sub-supply means for supplying the processing gas to said plasma forming region through the outer periphery of said antenna covering member.

19. A plasma processing apparatus according to claim 18, wherein said sub-supply means includes a plurality of sub-gas-passing holes formed in the outer periphery of said antenna covering member at predetermined intervals in the circumferential direction and opened in one surface of said antenna covering member and means for supplying the processing gas from said gas supply source to said sub-gas-passing holes, said processing gas being jetted out to said plasma forming region from said means for supplying said processing gas to said sub-gas-passing holes through said sub gas-passing holes.

20. A plasma processing apparatus according to claim 19, further comprising a blower plate disposed on at least one of gas jetting out sides of said gas passage hole of said antenna member and said sub-gas-passing holes of said antenna covering member and having a plurality of gas jetting-out ports to divide the processing gas to be jetted out into a plurality of jets.

21. A plasma processing apparatus according to claim 19, further comprising a blower plate disposed on the gas jetting-out side of said sub gas-passing holes of said antenna covering member and having a plurality of gas jetting-out ports directed to the center in such a manner that said processing gas to be jetted out is divided into a plurality of jets directed to the center of said plasma forming region.

22. A plasma processing apparatus comprising:

a processing container;

support means disposed in said processing container, for supporting a member to be processed which has a surface to be processed;

a microwave generator for generating microwaves;

a waveguide tube for guiding microwaves generated by said microwave generator into said processing container and a plurality of branched waveguide tubes branched from said waveguide tube; and

a flat antenna member electrically connected to said waveguide tube, facing, apart for an interval, said surface of said member to be processed, which is supported by said support means, and disposed to define a plasma forming region between said flat antenna member and said surface of said member to be processed,

said antenna member including a conductive plate and a multiplicity of slits formed in the conductive plate, the distribution and dimensions of slits being set so that an electrostatic field exponentially attenuating with the distance from said antenna member, is formed in said plasma forming region to generate plasma of said processing gas in said plasma forming region.

23. A plasma processing apparatus according to claim 22, wherein said branched waveguide tubes have a plurality of partition walls stood erect on said antenna member and extending in parallel to one another, each of said branched waveguide tubes is defined by adjacent two partition walls, and said slits extend between said adjacent two partition walls while having a predetermined angle from a direction in which said partition wall extends and are arranged adjacent to one another in the widthwise direction along said partition walls.

24. A plasma processing apparatus according to claim 23, wherein each of said slits has a length shorter than the guide wavelength of said microwave and the widthwise interval of adjacent slits is set to be shorter than said guide wavelength of said microwave.