Radial waveguide systems and methods for post-match control of microwaves

Patent metadata

Field	Value
Publication number	US-9299538-B2
Application number	US-201414221146-A
Country	US
Kind code	B2
Filing date	Mar 20, 2014
Priority date	Mar 20, 2014
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A system provides post-match control of microwaves in a radial waveguide. The system includes the radial waveguide, and a signal generator that provides first and second microwave signals that have a common frequency. The signal generator adjusts a phase offset between the first and second signals in response to a correction signal. The system also includes first and second electronics sets, each of which amplifies a respective one of the first and second microwave signals. The system transmits the amplified, first and second microwave signals into the radial waveguide, and matches an impedance of the amplified microwave signals to an impedance presented by the waveguide. The system also includes at least two monitoring antennas disposed within the waveguide. A signal controller receives analog signals from the monitoring antennas, determines the digital correction signal based at least on the analog signals, and transmits the correction signal to the signal generator.

First claim

What is claimed is:

1. A system that provides post-match control of microwaves in a radial waveguide, comprising:
the radial waveguide;
a signal generator that provides a first microwave signal and a second microwave signal, the first and second microwave signals having a common frequency, wherein the signal generator adjusts a phase offset between the first and second microwave signals in response to a digital correction signal;
a first electronics set and a second electronics set, wherein each of the first and second electronics sets:
amplifies a respective one of the first and second microwave signals to provide respective first and second amplified microwave signals,
transmits the respective one of the first and second amplified microwave signals into the radial waveguide, and
matches an impedance of the respective one of the first and second amplified microwave signals to an impedance presented by the radial waveguide;

at least two monitoring antennas disposed within the radial waveguide; and
a signal controller that:
receives analog signals from the at least two monitoring antennas;
determines the digital correction signal based at least on the analog signals from the at least two monitoring antennas; and
transmits the digital correction signal to the signal generator.

2. The system that provides post-match control of microwaves in a radial waveguide as recited in claim 1 , further comprising:
a target input device configured to provide a target parameter to the signal controller;
and wherein:
the signal controller determines the digital correction signal based on the analog signals from the at least two monitoring antennas and the target parameter.

3. The system that provides post-match control of microwaves in a radial waveguide as recited in claim 1 , wherein the first electronics set includes a tuner that matches an impedance of the first amplified microwave signal to an impedance presented by the radial waveguide;
wherein the signal generator adjusts the phase offset, and the tuner matches the impedance, concurrently with one another.

4. The system that provides post-match control of microwaves in a radial waveguide as recited in claim 1 , wherein the first electronics set includes:
a dummy load; and
a circulator that shunts power reflected back from the radial waveguide toward the first electronics set, into the dummy load.

5. The system that provides post-match control of microwaves in a radial waveguide as recited in claim 1 , wherein the first electronics set includes a solid state amplifier having a microwave field effect transistor that amplifies the first microwave signal to provide the first amplified microwave signal.

6. The system that provides post-match control of microwaves in a radial waveguide as recited in claim 1 , wherein the monitoring antennas are disposed proximate to locations at which the first and second electronics sets transmit the respective first and second amplified microwave signals into the radial waveguide.

7. A system for plasma processing of a workpiece, comprising:
a process chamber configured to create a plasma for the plasma processing;
a radial waveguide, adjacent to the process chamber, configured to generate microwaves for transmission to the process chamber to supply energy for the plasma;
a signal generator that provides a first microwave signal and a second microwave signal, the first and second microwave signals having a common frequency, wherein the signal generator adjusts a phase offset between the first and second microwave signals in response to a digital correction signal;
a first electronics set and a second electronics set, wherein each of the first and second electronics sets:
amplifies a respective one of the first and second microwave signals to provide an amplified microwave signal,
transmits the respective one of the first and second amplified microwave signals into the radial waveguide to produce microwaves therein; and
matches an impedance of the respective one of the first and second amplified microwave signals to an impedance presented by the radial waveguide;

at least two monitoring antennas disposed within the radial waveguide that produce analog signals in response to the microwaves; and
a signal controller that:
receives the analog signals from the at least two monitoring antennas,
determines the digital correction signal based at least on the analog signals, and
transmits the digital correction signal to the signal generator; and wherein the first electronics set includes:
a tuner that matches the impedance of the first amplified microwave signal to the impedance presented by the radial waveguide,
a dummy load, and
a circulator that shunts power reflected back from the radial waveguide toward the first electronics set, into the dummy load; and

the signal generator adjusts the phase offset, and the tuner matches the impedance, concurrently with one another.

8. The system for plasma processing of a workpiece as recited in claim 7 , wherein the radial waveguide comprises a radial line slot antenna for transmitting the microwaves into the process chamber.

9. The system for plasma processing of a workpiece as recited in claim 8 , further including a ceramic plate that bounds the process chamber adjacent to the radial line slot antenna of the radial waveguide, the ceramic plate supporting a pressure difference between the radial waveguide and the process chamber, while allowing the microwaves to propagate from the radial waveguide into the process chamber.

10. A method for controlling a plasma within a process chamber, comprising:
generating, with a signal generator, a first microwave signal and a second microwave signal, the first and second microwave signals having a common frequency, and a phase offset therebetween that is determined at least in part by the signal generator responding to a digital correction signal;
amplifying the first and second microwave signals to provide respective first and second amplified microwave signals;
transmitting the first and second amplified microwave signals into a radial waveguide proximate the process chamber, such that microwaves propagate from the radial waveguide into the process chamber to provide energy for the plasma;
generating analog signals from the microwaves with at least two monitoring antennas disposed within the radial waveguide;
determining the digital correction signal based at least on the analog signals from the at least two monitoring antennas; and
transmitting the digital correction signal to the signal generator.

11. The method for controlling a plasma within a process chamber as recited in claim 10 , wherein determining the digital correction signal comprises performing in-phase and quadrature-phase demodulation on each of the analog signals.

12. The method for controlling a plasma within a process chamber as recited in claim 11 , wherein performing in-phase and quadrature-phase demodulation comprises:
mixing a reference high frequency signal with one of the the analog signals to generate an intermediate frequency, and
generating digital in-phase and quadrature-phase signals from the intermediate frequency.

13. The method for controlling a plasma within a process chamber as recited in claim 12 , further comprising:
utilizing a microprocessor to generate the digital correction signal based on the digital in-phase and quadrature-phase signals;
and wherein generating the first microwave signal comprises:
generating an analog output at the intermediate frequency, utilizing the digital correction signal, and
mixing the analog output with the reference high frequency

Assignees

• Applied Materials Inc

Inventors

• Kobayashi Satoru
• Park Soonam
• Lubomirsky Dmitry

Classifications

• H01J7/24

  Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space · CPC title

• H01J37/244

  Detectors; Associated components or circuits therefor · CPC title

• H01J37/3299

  Feedback systems · CPC title

• H01J37/32302

  Plural frequencies · CPC title

• H01J37/32201 Primary

  Generating means · CPC title