RF pulsing within pulsing for semiconductor RF plasma processing

Patent metadata

Field	Value
Publication number	US-11342159-B2
Application number	US-201816888613-A
Country	US
Kind code	B2
Filing date	Nov 28, 2018
Priority date	Dec 7, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

A system and method for generating a radio frequency (RF) waveform are described. The method includes defining a train of on-off pulses separated by an off state having no on-off pulses. The method further includes applying a multi-level pulse waveform that adjusts a magnitude of each of the on-off pulses to generate an RF waveform. The method includes sending the RF waveform to an electrode.

First claim

The invention claimed is:

1. A method comprising:
defining a first on-off pulsed radio frequency (RF) clock, wherein the first on-off pulsed RF clock has a first plurality of square wave signals and a second plurality of square wave signals, wherein the first plurality of square wave signals and the second plurality of square wave signals are separated by an off state having no on-off pulses;
applying a first shaping waveform that adjusts a magnitude of the first on-off pulsed RF clock to generate a first shaped waveform;
generating a first shaped sinusoidal waveform based on the first shaped waveform; and
sending the first shaped sinusoidal waveform to a first electrode.

2. The method of claim 1 , wherein the first electrode is a coil or a substrate support.

3. The method of claim 1 , wherein the first on-off pulsed RF clock has an on state, the method further comprising:
inverting the first on-off pulsed RF clock to output an inverted square wave signal; and
outputting an amplified square waveform from a square wave signal and the inverted square wave signal;
wherein said applying the first shaping waveform includes adjusting a magnitude of the amplified square waveform to generate the first shaped waveform, and
wherein said generating the first shaped sinusoidal waveform includes extracting the first shaped sinusoidal waveform from the first shaped waveform.

4. The method of claim 3 , wherein said adjusting the magnitude of the amplified square waveform is performed to output a level-to-level shaped waveform or a multi-level shaped waveform or an arbitrary-shaped waveform.

5. The method of claim 1 , wherein the first on-off pulsed RF clock has an on state and the off state, wherein the first plurality of square wave signals has a first frequency greater than a second frequency of the on and off states and the second plurality of square wave signals has the first frequency.

6. The method of claim 1 , further comprising:
defining a second on-off pulsed RF clock, wherein the second on-off pulsed RF clock has a third plurality of square wave signals and a fourth plurality of square wave signals, wherein the third plurality of square wave signals and the fourth plurality of square wave signals are separated by an off state having no on-off pulses;
applying a second shaping waveform that adjusts a magnitude of the second on-off pulsed RF clock to generate a second shaped waveform;
generating a second shaped sinusoidal waveform based on the second shaped waveform; and
sending the second shaped sinusoidal waveform to a second electrode.

7. The method of claim 6 , wherein the second on-off pulsed RF clock is defined based on the first on-off pulsed RF clock.

8. The method of claim 7 , wherein the second on-off pulsed RF clock is inverted compared to the first on-off pulsed RF clock.

9. A method comprising:
generating a first clock signal having a radio frequency (RF);
providing a first pulsing signal;
filtering the first clock signal according to on and off states of the first pulsing signal to output a first on-off pulsed RF clock signal;
producing a first plurality of square wave signals from the first on-off pulsed RF clock signal;
generating a first amplified square waveform from the first plurality of square wave signals;
generating a first shaping waveform;
filtering a first direct current (DC) voltage associated with a first agile DC rail according to the first shaping waveform to generate a first filtered waveform;
shaping the first amplified square waveform based on the first filtered waveform to generate a first shaped waveform;
extracting a first shaped sinusoidal waveform from the first shaped waveform, the first shaped sinusoidal waveform being output based on a first shaped envelope defined by the first filtered waveform; and
providing RF power of the first shaped sinusoidal waveform for generating plasma for processing a substrate.

10. The method of claim 9 , wherein said producing the first plurality of square wave signals comprises:
allowing the first on-off pulsed RF clock signal to pass through to output a first one of the first plurality of square wave signals; and
inverting the first on-off pulsed RF clock signal to output a second one of the first plurality of square wave signals.

11. The method of claim 9 , wherein said shaping the first amplified square waveform based on the first filtered waveform to generate the first shaped waveform comprises applying an envelope of the first filtered waveform to the first amplified square waveform to conform an envelope of the first amplified square waveform to the envelope of the first filtered waveform.

12. The method of claim 9 , wherein said extracting the first shaped sinusoidal waveform from the first shaped waveform comprises removing higher order harmonics from the first shaped waveform to output a fundamental frequency waveform.

13. The method of claim 9 , wherein the first shaped envelope is a multi-level pulse-shaped envelope, or a level-to-level shaped envelope, or an arbitrary-shaped envelope.

14. The method of claim 9 , wherein said providing the first pulsing signal comprises providing the first pulsing signal at a frequency lower than the radio frequency.

15. The method of claim 9 ,
wherein said providing the first pulsing signal comprises providing a plurality of pulses to provide a plurality of instances of an on state and a plurality of instances of an off state,
wherein each of the plurality of instances of the on state of the first pulsing signal is followed by a corresponding one of the plurality of instances of the off state of the first pulsing signal and each of the plurality of instances of the off state of the first pulsing signal is followed by a corresponding one of the plurality of instances of the on state of the first pulsing signal,
wherein said generating the first clock signal comprises producing a plurality of pulses to provide a plurality of instances of an on state and a plurality of instances of an off state,
wherein each of the plurality of instances of the on state of the first clock signal is followed by a corresponding one of the plurality of instances of the off state of the first clock signal and each of the plurality of instances of the off state of the first clock signal is followed by a corresponding one of the plurality of instances of the on state of the first clock signal.

16. The method of claim 15 , wherein said filtering the first clock signal comprises filtering out a number of the plurality of pulses of the first clock signal according to the off state of the first pulsing signal.

17. The method of claim 9 , wherein the RF power of the first shaped sinusoidal waveform is provided to a top electrode of a plasma chamber, the method further comprising:
generating a second clock signal having a radio frequency;
inverting the first pulsing signal to output a second pulsing signal;
filtering the second clock signal according to on and off states of the second pulsing signal to output a second on-off pulsed RF clock signal;
producing a second plurality of square wave signals from the second on-off pulsed RF clock signal;
generating a second amplified square waveform from the second plurality of square wave signals;
generating a second shaping waveform;
filtering a second DC voltage associated with a second agile DC rail according to the second shaping waveform to generate a second filtered waveform;
shaping the second amplified square waveform based on the second filtered waveform to generate a second shaped waveform;
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Assignees

• Lam Res Corp

Inventors

• Long Maolin
• Wang Yuhou
• Wu Ying
• Paterson Alex

Classifications

• H03K5/02

  by amplifying (H03K5/04 takes precedence) · CPC title

• H01J37/32174 Primary

  Circuits specially adapted for controlling the RF discharge · CPC title

• H01J37/32146 Primary

  Amplitude modulation, includes pulsing · CPC title

• H01J37/32082

  Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence) · CPC title

• H03K3/80 Primary

  Generating trains of sinusoidal oscillations (by keying or interruption of sinusoidal oscillations H03C; for transmission of digital information H04L) · CPC title