Plasma processing apparatus for radiating microwave from rectangular waveguide through long slot to plasma chamber

• US 5,843,236 A
• Filed: 09/15/1995
• Issued: 12/01/1998
• Est. Priority Date: 09/16/1994
• Status: Expired due to Fees

• Current Assignee: Daihen Corporation
• Original Assignee: Daihen Corporation
• Inventors: Ishii, Akira, Amadatsu, Shigeki, Itadani, Koji, Kondo, Kazuki, Saijo, Tatsuya, Yoshiki, Hiroyuki, Aoyama, Takahiro
• Primary Examiner(s): Russel, Jeffrey E.
• Application Number:
  US08/529,282
• Time in Patent Office: 1,173 Days
• Field of Search: 333/99 PL, 315/111.21, 315/111.41, 315/111.51, 315/111.71, 156/345, 118/50.1, 118/620, 118/623, 118/717, 118/705, 118/706, 118/723 MP, 118/723 MW, 118/723 ME, 118/723 MR, 118/723 MA, 204/298.02, 204/298.08, 204/298.16, 204/298.17, 204/298.35, 204/298.37, 204/298.38, 216/69, 216/70, 427/571, 427/575, 438/726, 438/727, 438/728, 438/772
• US Class Current: 118/723.0MR
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32229 Waveguides
• CPC Class Codes: H01J 37/32238 Windows
• CPC Class Codes: H01J 37/32256 Tuning means
• CPC Class Codes: H01J 37/3266 Magnetic control means
• CPC Class Codes: H01J 37/3277 of continuous material

Abstract

In a plasma processing apparatus including a plasma chamber having a narrow window, and a rectangular waveguide for coupling with the plasma chamber, the rectangular waveguide has a long slot disposed in an E-plane thereof so as to oppose the narrow window of the plasma chamber and to extend along a waveguide-axis direction of the rectangular waveguide. There is further provided at least two long slots disposed in at least one rectangular waveguide, and the longitudinal length of each long slot is set to 1/2 or more of a free-space wavelength of the microwave. Further, the long slots are disposed so as to be parallel to each other such that adjacent long slots are shifted from each other by (2n-1)/4 of the free-space wavelength of the microwave in the waveguide-axis direction of the rectangular waveguide, where n is a natural number.

Claims

1. A plasma processing apparatus comprising:

a plasma chamber having a narrow window formed in a side wall thereof, an object to be processed being provided inside said narrow window;

a rectangular waveguide for coupling with said plasma chamber, said rectangular waveguide having a long slot disposed in an E-plane thereof so as to oppose to said narrow window of said plasma chamber and to extend along a waveguide-axis direction of said rectangular waveguide, said rectangular waveguide being provided so that the waveguide-axis direction of said rectangular waveguide is parallel to a longitudinal direction of said narrow window of said plasma chamber; and

microwave power supply means for supplying a microwave to said rectangular waveguide,

wherein the microwave is radiated from said rectangular waveguide to said plasma chamber through said long slot,

said plasma processing apparatus being characterized in further comprising;

at least two said long slots disposed in at least one said rectangular waveguide;

wherein the longitudinal length of said each long slot is set to 1/2 or more of a free-space wavelength of the microwave; and

wherein said long slots are disposed so as to be parallel to each other such that adjacent said long slots are shifted from each other by (2n-1)/4 of the free-space wavelength of the microwave in the waveguide-axis direction of said rectangular waveguide, where n is a natural number.

2. The plasma processing apparatus as claimed in claim 1, comprising:

at least two said rectangular waveguides each having at least one said long slot; and

further microwave power supply means for supplying a microwave to another one of said rectangular waveguides in a direction different from the direction of one of said rectangular waveguides adjacent to the another one of said rectangular waveguides.

3. The plasma processing apparatus as claimed in claim 2,

wherein each of said long slots is a slot array composed of a plurality of sub-slots disposed by equally dividing said long slot in the waveguide-axis direction of said rectangular waveguide,

said plasma processing apparatus further comprising:

a terminating unit provided at a terminating end of said rectangular waveguides and having a movable short-circuit plate provided so as to move along the waveguide-axis direction of said rectangular waveguide,

wherein said movable short-circuit plate is positioned so that center portions of peaks of a voltage standing wave generated in said rectangular waveguides are coincident with longitudinal center portions of said sub-slots, respectively.

4. The plasma processing apparatus as claimed in claim 1, further comprising:

one said rectangular waveguide having one long slot, said long slot being a slot array composed of a plurality of sub-slots disposed by equally dividing said long slot in the waveguide-axis direction of said rectangular waveguide; and

a terminating unit provided at a terminating end of said rectangular waveguide and having a movable short-circuit plate provided so as to move along the waveguide-axis direction of said rectangular waveguide,

wherein said movable short-circuit plate is positioned so that center portions of peaks of a voltage standing wave generated in said rectangular waveguide are coincident with longitudinal center portions of said sub-slots, respectively.

10. The plasma processing apparatus as claimed in claim 2, further comprising:

a microwave waveguide forming member provided between each said long slot and said narrow window of said plasma chamber and having at least two microwave waveguides each having a cross section identical to an opening shape of each said long slot; and

a dielectric made of a material that does not absorb any microwave, and said dielectric being inserted into each of said microwave waveguides at a position near a terminating end of each of said rectangular waveguides along the waveguide-axis direction of said rectangular waveguide, said dielectric reflecting a part of the microwave and transmitting another part of the microwave,

wherein the length of each said dielectric in the longitudinal direction of each said long slot is set to n/2 of a free-space wavelength of the microwave where n is a natural number, and

wherein an insertion length of each said dielectric into each said microwave waveguide is set by adjusting a microwave transmittance coefficient of each said dielectric so that an electric field intensity of the microwave along the longitudinal direction of said plasma chamber becomes substantially uniform.

5. A plasma processing apparatus comprising:

a plasma chamber having a narrow window disposed in a side wall thereof, an object to be processed being provided inside said narrow window;

a rectangular waveguide for coupling with said plasma chamber, said rectangular waveguide having a long slot disposed in an E-plane thereof so as to oppose to said narrow window of said plasma chamber and to extend along a waveguide-axis direction of said rectangular waveguide, said rectangular waveguide being provided so that the waveguide-axis direction of said rectangular waveguide is parallel to a longitudinal direction of said narrow window of said plasma chamber; and

microwave power supply means for supplying a microwave to said rectangular waveguide,

wherein the microwave is radiated from the rectangular waveguide to said plasma chamber through said long slot,

said plasma processing apparatus being characterized in that;

a longitudinal length of said long slot is set to 1/2 or more of a free-space wavelength of the microwave, said plasma processing apparatus further comprising;

a microwave waveguide forming member provided between said long slot and said narrow window of said plasma chamber, said microwave waveguide forming member having a microwave waveguide having a cross section identical to an opening shape of said long slot; and

a dielectric made of a material that does not absorb any microwave, said dielectric being inserted into said microwave waveguide at a position near a terminating end of said rectangular waveguide along the waveguide-axis direction of said rectangular waveguide, said dielectric reflecting a part of the microwave and transmitting another part of the microwave.

6. The plasma processing apparatus as claimed in claim 5,

wherein the length of said dielectric in the longitudinal direction of said long slot is set to n/2 of a free-space wavelength of the microwave where n is a natural number, and

wherein an insertion length of said dielectric into said microwave waveguide is set by adjusting a microwave transmittance coefficient of said dielectric so that an electric field intensity of the microwave along the longitudinal direction of said plasma chamber becomes substantially uniform.

7. A plasma processing apparatus comprising:

a plasma chamber having a narrow window disposed in a side wall thereof, an object to be processed being provided inside said narrow window;

a rectangular waveguide for coupling with said plasma chamber, said rectangular waveguide having a long slot disposed in an E-plane thereof so as to oppose to said narrow window of said plasma chamber and to extend along a waveguide-axis direction of said rectangular waveguide, said rectangular waveguide being provided so that the waveguide-axis direction of said rectangular waveguide is parallel to a longitudinal direction of said narrow window of said plasma chamber; and

microwave power supply means for supplying a microwave to said rectangular waveguide,

wherein the microwave is radiated from the rectangular waveguide to said plasma chamber through said long slot,

said plasma processing apparatus being characterized in that;

a longitudinal length of said long slot is set to 1/2 or more of a free-space wavelength of the microwave,

said plasma processing apparatus further comprising;

a movable short-circuit plate provided at a terminating end of said rectangular waveguide so as to move along the waveguide-axis direction of said rectangular waveguide over a length of 1/2 or more of a guide wavelength of the microwave; and

movement driving means for moving said movable short-circuit plate periodically or non-periodically along the waveguide-axis direction of said rectangular waveguide.

8. A plasma processing apparatus comprising:

a plasma chamber having a narrow window disposed in a side wall thereof, an object to be processed being provided inside said narrow window;

a rectangular waveguide for coupling with said plasma chamber, said rectangular waveguide having a long slot disposed in an E-plane thereof so as to oppose to said narrow window of said plasma chamber and to extend along a waveguide-axis direction of said rectangular waveguide, said rectangular waveguide being provided so that the waveguide-axis direction of said rectangular waveguide is parallel to a longitudinal direction of said narrow window of said plasma chamber; and

microwave power supply means for supplying a microwave to said rectangular waveguide,

wherein the microwave is radiated from the rectangular waveguide to said plasma chamber through said long slot,

said plasma processing apparatus being characterized in that;

a longitudinal length of said long slot is set to 1/2 or more of a free-space wavelength of the microwave,

said plasma processing apparatus further comprising;

a movable slot plate having an opening having a length shorter than a longitudinal length of said long slot in the waveguide-axis direction and having a width equal to a width of said long slot, said movable slot plate being disposed in a space between said long slot of said rectangular waveguide and said narrow window of said plasma chamber so as to move along the waveguide-axis direction of said rectangular waveguide so that said opening opposes to said long slot; and

movement driving means for moving said movable slot plate periodically or non-periodically over a length of 1/2 or more of the free-space wavelength of the microwave.

9. A plasma processing apparatus comprising:

a plasma chamber having a narrow window disposed in a side wall thereof, an object to be processed being provided inside said narrow window;

a rectangular waveguide for coupling with said plasma chamber, said rectangular waveguide having a long slot disposed in an E-plane thereof so as to oppose to said narrow window of said plasma chamber and to extend along a waveguide-axis direction of said rectangular waveguide, said rectangular waveguide being provided so that the waveguide-axis direction of said rectangular waveguide is parallel to a longitudinal direction of said narrow window of said plasma chamber; and

microwave power supply means for supplying a microwave to said rectangular waveguide,

wherein the microwave is radiated from the rectangular waveguide to said plasma chamber through said long slot,

said plasma processing apparatus being characterized in that;

a longitudinal length of said long slot is set to 1/2 or more of a free-space wavelength of the microwave,

said plasma processing apparatus further comprising;

magnetic-field generating means for generating a magnetic field in a space between said object provided in said plasma chamber and said narrow window, and for changing a direction and an intensity of the generated magnetic field.

11. The plasma processing apparatus as claimed in claim 9, further comprising:

at least two said rectangular waveguides each having at least one said long slot; and

further microwave power supply means for supplying a microwave to another one of said rectangular waveguides in a direction different from the direction of one of said rectangular waveguides adjacent to the another one of said rectangular waveguides, and

wherein said long slots are disposed so as to be parallel to each other such that adjacent said long slots are shifted from each other by (2n-1)/4 of the free-space wavelength of the microwave in the waveguide-axis direction of said rectangular waveguide, where n is a natural number.

12. The plasma processing apparatus as claimed in claim 11, further comprising:

a microwave waveguide forming member provided between said long slot and said narrow window of said plasma chamber, said microwave waveguide forming member having a microwave waveguide having a cross section identical to an opening shape of said long slot; and

a dielectric made of a material that does not absorb any microwave, said dielectric being inserted into said microwave waveguide at a position near a terminating end of said rectangular waveguide along the waveguide-axis direction of said rectangular waveguide, said dielectric reflecting a part of the microwave and transmitting another part of the microwave.

13. The plasma processing apparatus as claimed in claim 9, further comprising:

a microwave waveguide forming member provided between said long slot and said narrow window of said plasma chamber, said microwave waveguide forming member having a microwave waveguide having a cross section identical to an opening shape of said long slot; and

a dielectric made of a material that does not absorb any microwave, said dielectric being inserted into said microwave waveguide at a position near a terminating end of said rectangular waveguide along the waveguide-axis direction of said rectangular waveguide, said dielectric reflecting a part of the microwave and transmitting another part of the microwave,

wherein a length of said dielectric in the longitudinal direction of said long slot is set to n/2 of a free-space wavelength of the microwave where n is a natural number, and

wherein an insertion length of said dielectric into said microwave waveguide is set by adjusting a microwave transmittance coefficient of said dielectric so that an electric field intensity of the microwave along the longitudinal direction of said plasma chamber becomes substantially uniform.