Vacuum plasma generator

• US 20060196426A1
• Filed: 03/09/2006
• Published: 09/07/2006
• Est. Priority Date: 03/05/2005
• Status: Active Grant

• Current Assignee: Hüttinger Elektronik GmbH + Co. KG
• Original Assignee: Hüttinger Elektronik GmbH + Co. KG
• Inventors: Gluck, Michael, Hofstetter, Christoph, Hintz, Gerd
• Granted Patent: US 7,452,443 B2
• Time in Patent Office: Days
• US Class Current: 118/723.00R
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance

Abstract

A vacuum plasma generator is used for treating workpieces in a vacuum chamber. The vacuum plasma generator includes a mains connection for connection to a voltage supply network, and at least one mains rectifier. The at least one mains rectifier is connected to at least one first converter that generates at least one intermediate circuit voltage, a first RF signal generator, a second RF signal generator, and at least one 3 dB coupler. The first RF signal generator is connected to at least one intermediate circuit voltage, for generating a first signal of a basic frequency and of a first phase position. The second RF signal generator is connected to at least one intermediate circuit voltage, for generating a second signal of the basic frequency and of a second phase position. The least one 3 dB coupler couples the first and the second signal into an output signal of the generator.

Claims

1. A vacuum plasma generator for treating workpieces in a vacuum chamber, the vacuum plasma generator comprising:

a mains connection for connection to a voltage supply network;

at least one mains rectifier that is connected to;

at least one first converter that generates at least one intermediate circuit voltage;

a first RF signal generator that is connected at least one intermediate circuit voltage of the at least one first converter, and that generates a first signal of a basic frequency and of a first phase position;

a second RF signal generator that is connected to at least one intermediate circuit voltage of the at least one first converter, and that generates a second signal of the basic frequency and of a second phase position;

at least one 3 dB coupler that couples the first and the second signal and generates an output signal.

2. The vacuum plasma generator of claim 1, wherein the first RF signal generator and the second RF signal generator are connected to the same intermediate circuit voltage of the at least one first converter.

3. The vacuum plasma generator of claim 1, wherein the first and second RF signal generators are each designed as inverters that are driven by a control means.

4. The vacuum plasma generator of claim 3, wherein the control means is open-loop, closed-loop, or both open-loop and closed-loop.

5. The vacuum plasma generator of claim 3, wherein each inverter includes a half-bridge or a full bridge.

6. The vacuum plasma generator of claim 1, further comprising at least one capacitor for galvanic decoupling.

7. The vacuum plasma generator of claim 1, further comprising a pulse shaping network that is connected downstream of each of the first and second RF signal generators.

8. The vacuum plasma generator of claim 1, wherein:

the 3 dB coupler comprises at least one first and one second electric conductor that are spaced apart and are capacitively and inductively coupled to each other,

the first conductor represents the primary side of a transformer and the second conductor represents the secondary side of a transformer, and

the first and second conductors each having a winding number of n>

1.

9. The vacuum plasma generator of claim 8, wherein a length of the at least one first and/or one second conductor is <

λ

/4, where λ

is the wavelength of the RF signal.

10. The vacuum plasma generator of claim 1, wherein:

the 3 dB coupler comprises at least one first and one second electric conductor that are spaced apart, and are capacitively and inductively coupled to each other,

the first conductor represents the primary side of a transformer and the second conductor represents the secondary side of a transformer, and

at least one inductance increasing element is provided in a coupling region to increase the inductance of the conductors.

11. The vacuum plasma generator of claim 9, wherein a length of the at least one first and/or second conductor is <

λ

/4, where λ

is the wavelength of the RF signal.

12. The vacuum plasma generator of claim 1, wherein the 3 dB coupler has a characteristic wave impedance of <

50 ohms.

13. The vacuum plasma generator of claim 1, wherein the 3 dB coupler has a characteristic wave impedance of <

20 ohms.

14. The vacuum plasma generator of claim 1, wherein at least two converters are provided to generate intermediate circuit voltages, wherein each converter is associated with at least one RF signal generator.

15. The vacuum plasma generator of claim 1, further comprising a control means, wherein the at least one converter comprises an input connected to the control means.

16. The vacuum plasma generator of claim 15, wherein the control means is open-loop, closed-loop, or both open-loop and closed-loop.

17. The vacuum plasma generator of claim 15, wherein the control means is designed as a programmable logic component.

18. The vacuum plasma generator of claim 15, wherein the control means is a digital signal processor.

19. The vacuum plasma generator of claim 1, further comprising an impedance matching circuit that adjusts the impedance of the generator to a plasma load.

20. The vacuum plasma generator of claim 1, wherein the at least one converter is designed as a boost converter, a buck converter, or both a boost and a buck converter.

21. The vacuum plasma generator of claim 1, wherein the first RF signal generator generates a first signal of the basic frequency in the range between 1 and 30 MHz.

22. A vacuum plasma generator for treating workpieces in a vacuum chamber, the vacuum plasma generator comprising:

a mains connection coupled to a voltage supply network;

at least one mains rectifier connected to the mains connection;

at least one first converter connected to the mains rectifier and generating at least one intermediate circuit voltage;

a first RF signal generator that is connected to at least one intermediate circuit voltage of the at least one first converter, and that generates a first signal of a basic frequency, and of a first phase position;

a second RF signal generator that is connected to at least one intermediate circuit voltage of the at least one first converter, and that generates a second signal of the basic frequency, and of a second phase position; and

at least one 3 dB coupler that couples the first and the second signal and generates an output signal.

23. The vacuum plasma generator of claim 22, wherein the first RF signal generator and the second RF signal generator are connected to the same intermediate circuit voltage of the at least one first converter.

24. A method of treating workpieces in a vacuum chamber, the method comprising:

receiving a mains voltage from a voltage supply network;

generating at least one intermediate circuit voltage;

generating a first RF signal of a basic frequency, and of a first phase position, from the at least one intermediate circuit voltage;

generating a second RF signal of the basic frequency, and of a second phase position, from the at least one intermediate circuit voltage; and

coupling the first and the second signal and generating an output signal for the vacuum chamber using a 3 dB coupler.