Stable surface wave plasma source

• US 8,415,884 B2
• Filed: 09/08/2009
• Issued: 04/09/2013
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Chen, Lee, Zhao, Jianping, Funk, Merritt, Bravenec, Ronald V.
• Primary Examiner(s): Le, Tung X
• Application Number:
  US12/555,080
• Publication Number:
  US 20110057562A1
• Time in Patent Office: 1,309 Days
• Field of Search: 31511101-11191, 118/723.MW, 156/345.36, 156/345.41
• US Class Current: 315/111.01
• 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: H01L 21/67005 Apparatus not specifically provided for elsewhere processes per se H01L21/30, H01L21/46, H01L23/00; simple temporary support means, e.g. using adhesives, electric or magnetic means H01L21/68, H01L21/302
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

A surface wave plasma (SWP) source is described. The SWP source comprises an electromagnetic (EM) wave launcher configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of the EM wave launcher adjacent the plasma. The EM wave launcher comprises a slot antenna having a plurality of slots. The SWP source further comprises a first recess configuration formed in the plasma surface, wherein the first recess configuration is substantially aligned with a first arrangement of slots in the plurality of slots, and a second recess configuration formed in the plasma surface, wherein the second recess configuration is either partly aligned with a second arrangement of slots in the plurality of slots or not aligned with the second arrangement of slots in the plurality of slots. A power coupling system is coupled to the EM wave launcher and configured to provide the EM energy to the EM wave launcher for forming the plasma.

Claims

1. A surface wave plasma (SWP) source, comprising:

an electromagnetic (EM) wave launcher configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of said EM wave launcher adjacent said plasma, said EM wave launcher comprises a slot antenna having a plurality of slots formed therethrough configured to couple said EM energy from a first region above said slot antenna to a second region below said slot antenna;

a resonator plate positioned in said second region and having a lower surface of said resonator plate including said plasma surface of the EM wave launcher, wherein said resonator plate comprises a dielectric plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration substantially aligned with a first arrangement of slots in said plurality of slots, wherein said first recess configuration comprises;

a first plurality of cylindrical recesses, each of said first plurality of cylindrical recesses being characterized by a first depth and a first diameter or,

a first annular shelf, said first annular shelf being characterized by a first shelf depth and first shelf width, or

a first annular channel, said first annular channel being characterized by a first channel depth, a first inner channel radius, and a first outer channel radius, or

a combination of two or more thereof;

a second recess configuration formed in said plasma surface, said second recess configuration either partly aligned with a second arrangement of slots in said plurality of slots or not aligned with said second arrangement of slots in said plurality of slots, wherein said second recess configuration comprises;

a second plurality of cylindrical recesses, each of said second plurality of cylindrical recesses being characterized by a second depth and a second diameter, or

a second annular shelf, said second annular shelf being characterized by a second shelf depth and a second shelf width, or

a second annular channel, said second annular channel being characterized by a second channel depth, a second inner channel radius, and a second outer channel radius, or

a combination of two or more thereof; and

a power coupling system coupled to said EM wave launcher and configured to provide said EM energy to said EM wave launcher for forming said plasma, wherein said EM energy comprises an effective wavelength (λ

) of propagation in said resonator plate, and wherein;

said first diameter is about half said effective wavelength (λ

/2),

said second diameter is about half said effective wavelength (λ

/2) or about quarter said effective wavelength (λ

/4),

a first difference between said plate thickness and said first depth, said first shelf depth or said first channel depth is about half said effective wavelength (λ

/2) or about quarter said effective wavelength (λ

/4), and

a second difference between said plate thickness and said second depth, said second shelf depth, or said second channel depth is about half said effective wavelength (λ

/2) or about quarter said effective wavelength (λ

/4).

2. The SWP source of claim 1, wherein:

said power coupling system comprises a coaxial feed for coupling EM energy to said EM wave launcher, and

said slot antenna comprises one end coupled to an inner conductor of said coaxial feed and another end coupled to an outer conductor of said coaxial feed.

3. The SWP source of claim 1, wherein said EM wave launcher further comprises:

a slow wave plate positioned in said first region and configured to reduce an effective wavelength of said EM energy relative to a wavelength of said EM energy in free space.

4. The SWP source of claim 3, wherein said slow wave plate and said resonator plate each consist essentially of quartz or a high dielectric constant (high-k) material, said high dielectric constant material having a dielectric constant greater than a value of 4.

5. The SWP source of claim 1, wherein said power coupling system comprises:

a microwave source configured to produce microwave energy at 2.45 GHz;

a waveguide coupled to an outlet of said microwave source;

an isolator coupled to said waveguide and configured to prevent propagation of microwave energy back to said microwave source; and

a coaxial converter coupled to said isolator and configured to couple said microwave energy to a coaxial feed, wherein said coaxial feed is further coupled to said EM wave launcher.

6. The SWP source of claim 1, wherein said plurality of slots are arranged in pairs, and wherein each of said pair of slots comprises a first slot oriented orthogonal to a second slot.

7. The SWP source of claim 1, wherein said first recess configuration is located near an outer region of said plasma surface.

8. The SWP source of claim 1, wherein said second recess configuration is located near an inner region of said plasma surface.

9. The SWP source of claim 1, wherein said plate thickness is about half said effective wavelength (λ

/2).

10. The SWP source of claim 1, further comprising:

a third plurality of cylindrical recesses formed at a bottom of said first annular shelf or at a bottom of said first annular channel, each of said third plurality of cylindrical recesses being characterized by a third depth and a third diameter.

11. The SWP source of claim 10, wherein a third difference between said plate thickness and said third depth is about quarter said effective wavelength (λ

/4).

12. A surface wave plasma (SWP) source, comprising:

an electromagnetic (EM) wave launcher configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of said EM wave launcher adjacent said plasma, said EM wave launcher comprises a slot antenna having a plurality of slots formed therethrough configured to couple said EM energy from a first region above said slot antenna to a second region below said slot antenna;

a resonator plate positioned in said second region and having a lower surface of said resonator plate including said plasma surface of the EM wave launcher, wherein said resonator plate comprises a dielectric plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration substantially aligned with a first arrangement of slots in said plurality of slots, wherein said first recess comprises;

a first plurality of cylindrical recesses, each of said plurality of cylindrical recesses being characterized by a first depth and a first diameter or,

a first annular shelf, said first annular shelf being characterized by a first shelf depth and first shelf width, or

a first annular channel, said first annular channel being characterized by a first channel depth, a first inner channel radius, and a first outer channel radius, or

a combination of two or more thereof;

a second recess configuration formed in said plasma surface, said second recess configuration either partly aligned with a second arrangement of slots in said plurality of slots or not aligned with said second arrangement of slots in said plurality of slots, wherein said second recess configuration comprises;

a second plurality of cylindrical recesses, each of said second plurality of cylindrical recesses being characterized by a second depth and a second diameter, or

a second annular shelf, said second annular shelf being characterized by a second shelf depth and a second shelf width, or

a second annular channel, said second annular channel being characterized by a second channel depth, a second inner channel radius, and a second outer channel radius, or

a combination of two or more thereof; and

a power coupling system coupled to said EM wave launcher and configured to provide said EM energy to said EM wave launcher for forming said plasma, wherein;

said plate thickness ranges from about 25 mm to about 45 mm,

said first diameter ranges from about 25 mm to about 35 mm,

said second diameter ranges from about 25 mm to about 35 mm,

a first difference between said plate thickness and said first depth, said first shelf depth, or said first channel depth ranges from about 10 mm to about 35 mm, and

a second difference between said plate thickness and said second depth, said second shelf depth, or said second channel depth ranges from about 10 mm to about 35 mm.

13. The SWP source of claim 12, wherein said second diameter is less than said first diameter.

14. The SWP source of claim 12, wherein:

said power coupling system comprises a coaxial feed for coupling EM energy to said EM wave launcher, and

said slot antenna comprises one end coupled to an inner conductor of said coaxial feed and another end coupled to an outer conductor of said coaxial feed.

15. The SWP source of claim 12, wherein said EM wave launcher further comprises:

a slow wave plate positioned in said first region and configured to reduce an effective wavelength of said EM energy relative to a wavelength of said EM energy in free space.

16. The SWP source of claim 12, wherein said power coupling system comprises:

a microwave source configured to produce microwave energy at 2.45 GHz;

a waveguide coupled to an outlet of said microwave source;

an isolator coupled to said waveguide and configured to prevent propagation of microwave energy back to said microwave source; and

a coaxial converter coupled to said isolator and configured to couple said microwave energy to a coaxial feed, wherein said coaxial feed is further coupled to said EM wave launcher.

17. The SWP source of claim 12, wherein said plurality of slots are arranged in pairs, and wherein each of said pair of slots comprises a first slot oriented orthogonal to a second slot.

18. The SWP source of claim 12, further comprising:

a third plurality of cylindrical recesses formed at a bottom of said first annular shelf or at a bottom of said first annular channel, each of said third plurality of cylindrical recesses being characterized by a third depth and a third diameter.

19. A surface wave plasma (SWP) source, comprising:

an electromagnetic (EM) wave launcher configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of said EM wave launcher adjacent said plasma, said EM wave launcher comprises a slot antenna having a plurality of slots formed therethrough configured to couple said EM energy from a first region above said slot antenna to a second region below said slot antenna;

a resonator plate positioned in said second region and having a lower surface of said resonator plate including said plasma surface of the EM wave launcher, wherein said resonator plate comprises a dielectric plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration substantially aligned with a first arrangement of slots in said plurality of slots, wherein said first recess comprises;

a first plurality of cylindrical recesses, each of said plurality of cylindrical recesses being characterized by a first depth and a first diameter or,

a first annular shelf, said first annular shelf being characterized by a first shelf depth and first shelf width, or

a first annular channel, said first annular channel being characterized by a first channel depth, a first inner channel radius, and a first outer channel radius, or

a combination of two or more thereof;

a second recess configuration formed in said plasma surface, said second recess configuration either partly aligned with a second arrangement of slots in said plurality of slots or not aligned with said second arrangement of slots in said plurality of slots, wherein said second recess configuration comprises

a second plurality of cylindrical recesses, each of said second plurality of cylindrical recesses being characterized by a second depth and a second diameter, or

a second annular shelf, said second annular shelf being characterized by a second shelf depth and a second shelf width, or

a second annular channel, said second annular channel being characterized by a second channel depth, a second inner channel radius, and a second outer channel radius, or

a combination of two or more thereof;

a power coupling system coupled to said EM wave launcher and configured to provide said EM energy to said EM wave launcher for forming said plasma; and

a third recess configuration formed in said plasma surface, said third recess configuration not aligned with any of said plurality of slots, each of said third plurality of cylindrical recesses being characterized by a third depth and a third diameter.

20. A surface wave plasma (SWP) source, comprising:

an electromagnetic (EM) wave launcher configured to couple EM energy in a desired EM wave mode to a plasma in a process space by generating a surface wave on a plasma surface of said EM wave launcher adjacent said plasma, said EM wave launcher comprises a slot antenna having a plurality of slots formed therethrough configured to couple said EM energy from a first region above said slot antenna to a second region below said slot antenna, and a resonator plate positioned in said second region and having a lower surface of said resonator plate including said plasma surface of the EM wave launcher;

a first recess configuration formed in said plasma surface, said first recess configuration substantially aligned with a first arrangement of slots in said plurality of slots;

means for stabilizing said plasma for a pressure in said process space ranging from about 2 mtorr to about 1 torr, said means for stabilizing said plasma being formed in said plasma surface of said resonator plate;

means for uniformly generating said plasma in said process space; and

a power coupling system coupled to said EM wave launcher and configured to provide said EM energy to said EM wave launcher for forming said plasma.