Magnetically enhanced microwave plasma generating apparatus

• US 6,054,016 A
• Filed: 02/27/1998
• Issued: 04/25/2000
• Est. Priority Date: 09/26/1997
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Electric Engineering Co Ltd (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Electric Engineering Co Ltd (Mitsubishi Electric Corporation)
• Inventors: Oku, Kouji, Nakaguma, Shinji, Hanazaki, Minoru, Tsuchihashi, Masaaki, Ono, Kouichi, Komemura, Toshio, Tuda, Mutumi
• Primary Examiner(s): Nguyen, Nam
• Assistant Examiner(s): Cantelmo, Gregg
• Application Number:
  US09/031,706
• Time in Patent Office: 788 Days
• Field of Search: 204/298.38, 204/298.37, 156/345, 118/723 MW, 118/723 MA, 118/723 ME, 118/723 MR, 118/723 AN
• US Class Current: 156/345.42
• 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 37/32688 Multi-cusp fields
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

There is provided a plasma generating apparatus comprising: a waveguide for guiding a microwave; a vacuum vessel connected to the waveguide, having a means for supplying a gas for discharging electrons and a means for evacuating; and a dielectric member in a tube-like shape or a rod-like shape which is inserted in the vacuum vessel, wherein the dielectric member is provided with a means for emitting the microwave, whereby it is possible to apply the electric power of microwave effectively to plasma of high density exceeding so-called cut-off density and to homogenize the distribution of plasma in the vacuum vessel.

Claims

1. A plasma generating apparatus comprising:

a waveguide for guiding microwaves;

a vacuum vessel connected to the waveguide, having a means for supplying a gas to the vacuum vessel for discharging electrons and a means for evacuating the vacuum vessel;

a dielectric member having a tube-like shape or a rod-like shape, extending into the vacuum vessel, and comprising means for emitting microwaves; and

means, disposed outside of the vacuum vessel, for generating a first magnetic field inside the vacuum vessel such that the dielectric member is in a relatively weak magnetic field region of the first magnetic field.

2. The plasma generating apparatus according to claim 1, wherein

the means for emitting microwaves is a slit or an antenna provided in a wall of the waveguide.

3. The plasma generating apparatus according to claim 1, wherein

the dielectric member comprises a dielectric material through which microwaves are permeable.

4. The plasma generating apparatus according to claim 1, wherein

the dielectric member is located in a weak magnetic field region having a magnetic field strength of 100 G or less.

5. The plasma generating apparatus according to claim 1, wherein the weak magnetic field region has a magnetic field strength of 100 G or less.

6. The plasma generating apparatus according to claim 1, wherein the first magnetic field has a magnetic field strength sufficient to cause an electron cyclotron resonance and to start a discharge using the electron cyclotron resonance.

7. The plasma generating apparatus according to claim 1, wherein

the means for generating a magnetic field is a permanent magnet.

8. The plasma generating apparatus according to claim 1, further comprising an electromagnetic coil for generating a component of a second magnetic field to be superposed on a component of the first magnetic field, the electromagnetic coil being disposed outside of the vacuum vessel.

9. The plasma generating apparatus according to claim 3, wherein the dielectric member comprises at least one of quartz, glass, polytetrafluoroethylene and ceramic.