Stable surface wave plasma source

• US 8,669,705 B2
• Filed: 03/14/2013
• Issued: 03/11/2014
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Chen, Lee, Zhao, Jianping, Bravenec, Ronald V., Funk, Merritt
• Primary Examiner(s): Le, Tung X
• Application Number:
  US13/830,090
• Publication Number:
  US 20130264938A1
• Time in Patent Office: 362 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 at least one slot. The SWP source further comprises a first recess configuration and a second recess configuration formed in the plasma surface, wherein at least one first recess of the first recess configuration differs in size and/or shape from at least one second recess of the second recess configurations. 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 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 at least one slot 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 plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration having at least one first recess characterized by a first shape and a first size;

a second recess configuration formed in said plasma surface, said second recess configuration having at least one second recess characterized by a second shape and a second size; 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 at least one first recess differs from said at least one second recess in size, or shape, or size and shape, and wherein said first size is characterized by a first width and a first depth, said first width and said first depth range in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2), and wherein said second size is characterized by a second width and a second depth, said second width and said second depth range in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2).

2. The SWP source of claim 1, wherein said first recess configuration comprises:

at least one first recess characterized by a first width and a first depth, said at least one first recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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.

3. The SWP source of claim 2, wherein said second recess configuration comprises:

at least one second recess characterized by a second width and a second depth, said at least one second recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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.

4. The SWP source of claim 2, further comprising:

at least one third recess formed at a bottom of said first annular shelf or at a bottom of said first annular channel, said at least one third recess being characterized by a third depth and a third diameter.

5. The SWP source of claim 4, wherein a third difference between said plate thickness and said third depth is about quarter said effective wavelength (λ

/4).

6. 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.

7. 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 said effective wavelength of said EM energy relative to a wavelength of said EM energy in free space.

8. The SWP source of claim 7, 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.

9. 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.

10. The SWP source of claim 1, wherein said at least one slot includes a plurality of slots that are arranged in pairs, and wherein each of said pair of slots comprises a first slot oriented orthogonal to a second slot.

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

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

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

/2).

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

an electromagnetic (EM) wave launcher configured to couple EM energy 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 at least one slot 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 plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration having at least one first recess characterized by a first shape, a first size, a first width and a first depth, said at least one first recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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 having at least one second recess characterized by a second shape and a second size; 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 at least one first recess differs from said at least one second recess in size, or shape, or size and shape, and wherein;

said first width ranges in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2); and

said first depth, a first difference between said plate thickness and said first depth, said first shelf depth, or said first channel depth ranges in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2).

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

an electromagnetic (EM) wave launcher configured to couple EM energy 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 at least one slot 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 plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration having at least one first recess characterized by a first shape, a first size, a first width and a first depth, said at least one first recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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 having at least one second recess characterized by a second shape, a second size, a second width and a second depth, said at least one second recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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 at least one first recess differs from said at least one second recess in size, or shape, or size and shape, and wherein;

said second width ranges in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2); and

said second depth, a second difference between said plate thickness and said second depth, said second shelf depth, or said second channel depth ranges in size from about a quarter said effective wavelength (λ

/4) to about half said effective wavelength (λ

/2).

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

an electromagnetic (EM) wave launcher configured to couple EM energy 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 at least one slot 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 plate having a plate diameter and a plate thickness;

a first recess configuration formed in said plasma surface, said first recess configuration having at least one first recess characterized by a first shape, a first size, a first width and a first depth, said at least one first recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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 having at least one second recess characterized by a second shape, a second size, a second width and a second depth, said at least one second recess having a cylindrical geometry, a conical geometry, a frusto-conical geometry, a spherical geometry, an aspherical geometry, a rectangular geometry, or a pyramidal geometry, 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 at least one first recess differs from said at least one second recess in size, or shape, or size and shape, and wherein;

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

said first width ranges from about 25 mm to about 35 mm;

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

said first depth, 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

said second depth, 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.

17. The SWP source of claim 16, wherein said second width is less than said first width.