Matchless plasma source for semiconductor wafer fabrication

Patent metadata

Field	Value
Publication number	US-10638593-B2
Application number	US-201916356180-A
Country	US
Kind code	B2
Filing date	Mar 18, 2019
Priority date	Oct 18, 2017
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A matchless plasma source is described. The matchless plasma source includes a controller that is coupled to a direct current (DC) voltage source of an agile DC rail to control a shape of an amplified square waveform that is generated at an output of a half-bridge transistor circuit. The matchless plasma source further includes the half-bridge transistor circuit used to generate the amplified square waveform to power an electrode, such as an antenna, of a plasma chamber. The matchless plasma source also includes a reactive circuit between the half-bridge transistor circuit and the electrode. The reactive circuit has a high-quality factor to negate a reactance of the electrode. There is no radio frequency (RF) match and an RF cable that couples the matchless plasma source to the electrode.

First claim

The invention claimed is:

1. A matchless plasma source comprising:
a controller configured to output a control signal having a setting value;
a signal generator coupled to the controller for receiving the setting value, wherein the signal generator is configured to generate a radio frequency (RF) signal having an operating frequency specified in the setting value;
a gate driver coupled to the signal generator, wherein the gate driver is configured to output a plurality of pulsed signals using the radio frequency signal; and
an amplification circuit coupled to an output of the gate driver for receiving the plurality of pulsed signals to output an amplified waveform, wherein the amplification circuit is coupled to an arbitrary waveform generator to shape the amplified waveform.

2. The matchless plasma source of claim 1 , wherein the signal generator is a square wave oscillator, wherein the RF signal is a square wave signal that pulses between a first level and a second level.

3. The matchless plasma source of claim 1 , wherein the gate driver includes a gate driver sub-portion, a capacitor, a resistor, and a pulse transformer, wherein the capacitor and the resistor are coupled to the gate driver sub-portion and to the pulse transformer.

4. The matchless plasma source of claim 3 , wherein the gate driver sub-portion includes a first gate driver and a second gate driver, wherein the first and second gate drivers are coupled to the signal generator, wherein the capacitor is coupled to the first gate driver and the resistor is coupled to the second gate driver.

5. The matchless plasma source of claim 4 , wherein the pulse transformer has a primary winding and a plurality of secondary windings, wherein the primary winding is coupled to the capacitor and the resistor, wherein the plurality of secondary windings are coupled to the amplification circuit.

6. The matchless plasma source of claim 5 , wherein the amplification circuit includes a plurality of transistors and a direct current (DC) voltage source, wherein the DC voltage source is coupled to the plurality of transistors, wherein each of the plurality of secondary windings is coupled to a different one of the plurality of transistors.

7. The matchless plasma source of claim 6 , wherein the arbitrary waveform generator is coupled to the DC voltage source, wherein the arbitrary waveform generator is configured to provide a shaping control signal to the DC voltage source to vary a magnitude of a DC voltage that is output from the DC voltage source, wherein the magnitude of the DC voltage is varied to change a shape of an envelope of the amplified waveform to shape the amplified waveform.

8. The matchless plasma source of claim 1 , wherein one of the plurality of pulsed signals that is output from the gate driver is in reverse synchronization with another one of the plurality of pulsed signals output from the gate driver.

9. A method comprising:
providing, by a controller, a control signal having a setting value;
generating, by a signal generator, a radio frequency (RF) signal having an operating frequency specified in the setting value;
outputting, by a gate driver, a plurality of pulsed signals by using the radio frequency signal; and
receiving, by an amplification circuit, the plurality of pulsed signals to output an amplified waveform that is shaped according to a shaping control signal.

10. The method of claim 9 , wherein the RF signal is a square wave signal that pulses between a first level and a second level.

11. The method of claim 9 , wherein said outputting the plurality of pulsed signals by using the radio frequency signal comprises:
amplifying, by a gate driver sub-portion of the gate driver, the RF signal to output an amplified RF signal, wherein the amplified RF signal has a first directionality of flow and a second directionality of flow,
wherein the plurality of pulsed signals are output according to the first directionality of flow and the secondary directionality of flow.

12. The method of claim 11 , wherein the plurality of pulsed signals are reversely synchronized with respect to each other based on the first directionality of flow and the second directionality of flow.

13. The method of claim 9 , wherein said outputting the plurality of pulsed signals by using the radio frequency signal comprises amplifying the RF signal to output an amplified RF signal, wherein the amplified RF signal has a first directionality of flow and a second directionality of flow, the method further comprising:
applying a capacitance to the amplified RF signal when the amplified RF signal has the first directionality of flow; and
applying a resistance to the amplified RF signal when the amplified RF signal has the second directionality of flow.

14. The method of claim 9 , further comprising:
generating a direct current (DC) voltage according to the shaping control signal;
providing the DC voltage to shape an envelope of the amplified waveform.

15. A system comprising:
a matchless plasma source including:
a controller configured to output a control signal having a setting value;
a signal generator coupled to the controller for receiving the setting value, wherein the signal generator is configured to generate a radio frequency (RF) signal having an operating frequency specified in the setting value;
a gate driver coupled to the signal generator, wherein the gate driver is configured to output a plurality of pulsed signals using the radio frequency signal; and
an amplification circuit coupled to an output of the gate driver for receiving the plurality of pulsed signals to output an amplified waveform, wherein the amplification circuit is coupled to an arbitrary waveform generator to shape the amplified waveform;

a reactive circuit coupled to the matchless plasma source for modifying the amplified waveform to output a sinusoidal RF waveform; and
a plasma chamber coupled to the reactive circuit for receiving the sinusoidal RF waveform.

16. The system of claim 15 , wherein the signal generator is a square wave oscillator, wherein the RF signal is a square wave signal that pulses between a first level and a second level.

17. The system of claim 15 , wherein the gate driver includes a gate driver sub-portion, a capacitor, a resistor, and a pulse transformer, wherein the capacitor and the resistor are coupled to the gate driver sub-portion and to the pulse transformer.

18. The system of claim 17 , wherein the gate driver sub-portion includes a first gate driver and a second gate driver, wherein the first and second gate drivers are coupled to the signal generator, wherein the capacitor is coupled to the first gate driver and the resistor is coupled to the second gate driver.

19. The system of claim 15 , wherein the reactive circuit is a variable capacitor and the plasma chamber includes a transformer coupled plasma (TCP) coil.

20. The system of claim 15 , wherein the controller is coupled to the reactive circuit to change a capacitance of the reactive circuit.

Assignees

• Lam Res Corp

Inventors

• Long Maolin
• Wang Yuhou
• Marsh Ricky
• Paterson Alex

Classifications

• H05H2242/10

  Cooling arrangements · CPC title

• H01J37/32183 Primary

  Matching circuits · CPC title

• H05H1/46 Primary

  using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) · CPC title

• H03F3/2173

  of the bridge type · CPC title

• H05H2001/4652

  Electricity · mapped topic