Matching network for RF plasma source

• US 7,298,091 B2
• Filed: 02/01/2002
• Issued: 11/20/2007
• Est. Priority Date: 02/01/2002
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Leung, Ka-Ngo, Pickard, Daniel S.
• Primary Examiner(s): Lee; Wilson
• Application Number:
  US10/060,826
• Publication Number:
  US 20030146803A1
• Time in Patent Office: 2,118 Days
• Field of Search: 315/111.21, 315/111.41, 315/111.51, 315/111.71, 315/111.81, 31511101-11191, 118/723.I, 118/723.MR, 118/723.MA, 118/723.AN, 156/643.1, 156/345, 156/345.28, 250/492.21, 250/251, 333/17.3, 333/32
• US Class Current: 315/111.51
• CPC Class Codes: H01J 2237/31749 Focused ion beam
• CPC Class Codes: H03H 7/38 Impedance-matching networks

Abstract

A compact matching network couples an RF power supply to an RF antenna in a plasma generator. The simple and compact impedance matching network matches the plasma load to the impedance of a coaxial transmission line and the output impedance of an RF amplifier at radio frequencies. The matching network is formed of a resonantly tuned circuit formed of a variable capacitor and an inductor in a series resonance configuration, and a ferrite core transformer coupled to the resonantly tuned circuit. This matching network is compact enough to fit in existing compact focused ion beam systems.

Claims

1. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration;

a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer and said RF antenna being connected to another end of the winding of said ferrite core transformer.

2. The matching network of claim 1 wherein the transformer comprises a secondary winding which couples the transformer to both the tunable circuit and RF antenna and a primary winding.

3. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer coupled to the resonantly tunable circuit,

wherein a secondary winding of the transformer is a single-turn winding and a primary winding of the transformer is a multi-turn winding, the secondary winding is coupled to the tunable circuit.

4. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer having a single-turn secondary winding and a multi-turn primary winding, and the resonantly tunable circuit being connected to the secondary winding,

wherein the transformer further comprises a core which is made of a plurality of ferrite cores.

5. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer having a secondary winding that couples the transformer to the resonantly tunable circuit, and also having a primary winding,

wherein the transformer further comprises a core which is made of a plurality of ferrite cores.

6. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration; and

,

a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer, the one end of a winding of said ferrite core transformer being a secondary winding that couples said ferrite core transformer to said resonantly tunable circuit and said ferrite core transformer also having a primary winding,

wherein the turn ratio between the primary winding and the secondary winding ranges from 3;

1 to 8;

1.

7. The matching network of claim 6 wherein the turn ratio between the primary winding and the secondary winding is selected to transform the plasma impedance of the plasma generator to 50 Ω

.

8. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer having a secondary winding that couples the transformer to the resonantly tunable circuit, and also having a primary winding,

wherein the turn ratio between the primary winding and the secondary winding ranges from 3;

1 to 8;

1, and the transformer comprises a core made of 12 ferrite cores with a 1.25 inch OD and 0.75 inch ID, made of M-type ferrite.

9. The matching network of claim 8 wherein the variable capacitor has a capacity range of 5-125 pF.

10. The matching network of claim 9 wherein the network fits within a cylindrical volume 6 inches in diameter and 8 inches long.

11. A matching network for coupling an RF power supply to an RF antenna in a plasma generator, comprising:

a resonantly tunable circuit formed of a variable capacitor and inductor in a series resonance configuration;

a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer; and

,

an RF power supply connected through a 50 Ω

coaxial cable to an input of the matching network and the RF antenna (inductive coil) connected to an output of the matching network.

12. A plasma ion or electron source, comprising:

an RF power supply;

a coaxial cable connected to the RE power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer, said resonantly tunable circuit being connected to one end of a winding of said ferrite core transformer;

an RF antenna connected to an output of the matching network;

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma.

13. The plasma ion or electron source of claim 12 wherein the transformer comprises a secondary winding which couples the transformer to the tunable circuit and a primary winding.

14. A plasma ion or electron source, comprising:

an RF power supply;

a coaxial cable connected to the RF power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer coupled to the resonantly tunable circuit;

an RF antenna connected to an output of the matching network; and

,

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma,

wherein a secondary winding of the transformer is a single-turn winding and a primary winding of the transformer is a multi-turn winding, and the secondary winding couples the transformer to the resonantly tunable circuit.

16. The plasma ion or electron source of claim 14 wherein the turn ratio between the primary winding and the secondary winding ranges from 3:

1 to 8;

1.

17. The plasma ion or electron source of claim 14 wherein the coaxial cable has an impedance of 50 Ω

and the turn ratio between the primary winding and the secondary winding is selected to transform the plasma impedance of the plasma generator to 50 Ω

.

15. A plasma ion or electron source, comprising:

an RF power supply;

a coaxial cable connected to the RF power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; and

,

a ferrite core transformer having a single-turn secondary winding and a multi-turn primary winding, and the resonantly tunable circuit being connected to the secondary winding;

wherein there is an RF antenna connected to an output of the matching network; and

,

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma; and

,

wherein the transformer further comprises a core which is made of a plurality of ferrite cores.

18. A plasma ion electron source comprising:

an RF power supply;

a coaxial cable connected to the RF power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration; and

,

a ferrite core transformer coupled to the resonantly tunable circuit,

wherein there is an RF antenna connected to an output of the matching network; and

,

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma; and

,

wherein the plasma ion or electron generator is a multicusp plasma generator.

19. The plasma ion or electron source of claim 18 wherein the source is a part of a compact focused ion beam system.

20. The plasma ion or electron source of claim 19 wherein the matching network fits within a cylindrical cavity 6 inches in diameter and 8 inches long.

21. A plasma ion or electron source, comprising:

an RF power supply;

a coaxial cable connected to the RF power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer coupled to the resonantly tunable circuit;

an RF antenna connected to an output of the matching network; and

,

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma,

wherein the transformer comprises both a single-turn secondary winding that couples the transformer to the tunable circuit and a multi-turn primary winding, and the transformer further comprises a core that is made of a plurality of ferrite cores.

22. A plasma ion or electron source, comprising:

an RF power supply;

a coaxial cable connected to the RF power supply;

a matching network having an input connected to the coaxial cable, the matching network comprising;

a resonantly tunable circuit formed of a variable capacitor and an inductor in a series resonance configuration;

a ferrite core transformer coupled to the resonantly tunable circuit;

an RF antenna connected to an output of the matching network; and

,

a plasma ion or electron generator having the RF antenna mounted therein for inductively generating a plasma,

wherein the plasma ion or electron generator is a multicusp plasma generator.

23. The plasma ion or electron source of claim 22 wherein the source is a part of a compact focused ion beam system.

24. The plasma ion or electron source of claim 23 wherein the matching network fits within a cylindrical cavity 6 inches in diameter and 8 inches long.