Variable output impedance RF generator

Patent metadata

Field	Value
Publication number	US-11004660-B2
Application number	US-201916697173-A
Country	US
Kind code	B2
Filing date	Nov 26, 2019
Priority date	Nov 30, 2018
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

Various RF plasma systems are disclosed that do not require a matching network. In some embodiments, the RF plasma system includes an energy storage capacitor; a switching circuit coupled with the energy storage capacitor, the switching circuit producing a plurality of pulses with a pulse amplitude and a pulse frequency, the pulse amplitude being greater than 100 volts; a resonant circuit coupled with the switching circuit. In some embodiments, the resonant circuit includes: a transformer having a primary side and a secondary side; and at least one of a capacitor, an inductor, and a resistor. In some embodiments, the resonant circuit having a resonant frequency substantially equal to the pulse frequency, and the resonant circuit increases the pulse amplitude to a voltage greater than 2 kV.

First claim

That which is claimed:

1. An RF system comprising:
an energy storage capacitor;
a switching circuit coupled with the energy storage capacitor, the switching circuit producing a plurality of pulses with a pulse amplitude and a pulse frequency, the pulse amplitude being greater than 100 volts;
a resonant circuit coupled with the switching circuit, the resonant circuit comprising:
a transformer having a primary side and a secondary side; and
a circuit element selected from the group consisting a capacitor, an inductor, and a resistor,
the resonant circuit having a resonant frequency substantially equal to the pulse frequency, and the resonant circuit increases the pulse amplitude to a voltage greater than 2 kV; and

an energy recovery circuit coupled with the energy storage capacitor and the secondary side of the transformer, the energy recovery circuit comprising a diode and an inductor.

2. The RF system according to claim 1 , further comprising a plasma chamber coupled with the resonant circuit.

3. The RF system according to claim 1 , wherein the switching circuit comprises either a full-bridge driver or a half-bridge driver.

4. The RF system according to claim 1 , wherein the resonant circuit comprises an inductor, and the resonant frequency comprises

f
resonant

≈

1

2
⁢
π
⁢

(
L
)

⁢

(
C
)

,

where the inductance L includes any stray inductance of the transformer and the inductance of the inductor, and the capacitance C includes any stray capacitance of the transformer.

5. The RF system according to claim 1 , wherein the resonant circuit comprises a capacitor, and the resonant frequency comprises

f
resonant

≈

1

2
⁢
π
⁢

(
L
)

⁢

(
C
)

,

where the inductance L includes any stray inductance of the transformer, and the capacitance C includes any stray capacitance of the transformer and the capacitance of the capacitor.

6. An RF plasma system comprising:
a high voltage switching power supply producing a plurality of pulses with a pulse amplitude and a pulse frequency, the pulse amplitude being greater than 100 volts; and
a resonant circuit coupled with the switching power supply, the resonant circuit having a resonant frequency substantially equal to the pulse frequency and the resonant circuit increases the amplitude of the plurality of pulses to a voltage greater than 2 kV; and
a plasma chamber coupled with the resonant circuit.

7. The RF plasma system according to claim 6 , further comprising a transformer coupled with the resonant circuit.

8. The RF plasma system according to claim 6 , further comprising a resistive output stage.

9. The RF plasma system according to claim 6 , further comprising an energy recovery stage.

10. The RF plasma system according to claim 6 , further comprising a bias compensation circuit.

11. The RF plasma system according to claim 6 , wherein either or both the inductance (L) and/or the capacitance (C) of the transformer determine the resonant frequency according to:

f
resonant

≈

1

2
⁢
π
⁢

(
L
)

⁢

(
C
)

.

12. The RF plasma system according to claim 6 , wherein the resonant frequency comprises

f
resonant

≈

1

2
⁢
π
⁢

(
L
)

⁢

(
C
)

,

where the inductance L includes any stray inductance of the transformer and the capacitance C includes any stray capacitance of the transformer.

13. The RF plasma system according to claim 6 , wherein the high voltage switching power supply comprises either a full-bridge driver or a half-bridge driver.

14. The RF plasma system according to claim 6 , wherein the switching power supply is driven with a frequency selected from the group consisting of 400 kHz, 0.5 MHz, 2.0 MHz, 4.0 MHz, 13.56 MHz, 27.12 MHz, 40.68 MHz, and 50 MHz.

15. An RF plasma system comprising:
a high voltage switching power supply producing a plurality of pulses with a pulse amplitude and a pulse frequency, the pulse amplitude being greater than 100 volts and the pulse frequency being greater than 100 kHz;
an inductively coupled plasma source comprising a coil that is electrically coupled with the high voltage switching power supply; and
a capacitor, wherein the capacitor and the inductance of the inductively coupled plasma source resonate with a resonant frequency substantially equal to the pulse frequency.

16. The RF plasma according to claim 15 , wherein the resonant frequency comprises

f
resona

Assignees

• Eagle Harbor Tech Inc

Inventors

• Prager James
• Ziemba Timothy

Classifications

• H03K17/56

  by the use, as active elements, of semiconductor devices (using diodes H03K17/74) · CPC title

• H03K3/57

  the switching device being a semiconductor device · CPC title

• H03K3/36

  by the use, as active elements, of semiconductors, not otherwise provided for · CPC title

• H02M11/00

  Power conversion systems not covered by the preceding groups · CPC title

• H01J37/32183 Primary

  Matching circuits · CPC title