Microwave output device and plasma processing apparatus

Patent metadata

Field	Value
Publication number	US-11587769-B2
Application number	US-202117381698-A
Country	US
Kind code	B2
Filing date	Jul 21, 2021
Priority date	Jul 22, 2020
Publication date	Feb 21, 2023
Grant date	Feb 21, 2023

Abstract

A device includes a microwave generator configured to generate a microwave having a bandwidth, an output unit, a directional coupler and a measurer. The microwave generator generates a microwave a power of which is pulse-modulated to be a High level and a Low level. A set carrier pitch is set to satisfy a preset condition. The preset condition includes a condition that a value obtained by dividing a set pulse frequency by the set carrier pitch or a value obtained by dividing the set carrier pitch by the set pulse frequency is not an integer and a condition that an ON-time of the High level is equal to or larger than 50%. The microwave generator averages a first High measurement value and a first Low measurement value in a preset moving average time longer than a sum of the ON-time of the High level at a preset sampling interval.

First claim

We claim:

1. A microwave output device, comprising:
a microwave generator configured to generate a microwave having a median frequency, a bandwidth and a carrier pitch respectively corresponding to a set frequency, a set bandwidth and a set carrier pitch instructed from a control device, a power of the microwave being pulse-modulated such that a pulse frequency, a duty ratio, a High level and a Low level become a set pulse frequency, a set duty ratio, a set power of High level and a set power of Low level instructed from the control device;
an output unit configured to output the microwave propagated from the microwave generator;
a first directional coupler configured to output a part of a progressive wave propagated from the microwave generator to the output unit; and
a measurer configured to determine a first High measurement value and a first Low measurement value respectively indicating a High level and a Low level of a power of the progressive wave in the output unit, based on the part of the progressive wave outputted from the first directional coupler,
wherein a reciprocal of the set carrier pitch becomes a longest cycle among power variation cycles of the microwave having the bandwidth, and the set carrier pitch is set to satisfy a preset condition,
the preset condition includes a condition that a value obtained by dividing the set pulse frequency by the set carrier pitch or a value obtained by dividing the set carrier pitch by the set pulse frequency is not an integer and a condition that an ON-time of the High level with respect to a set cycle in the set duty ratio is equal to or larger than 50%,
the microwave generator averages the first High measurement value and the first Low measurement value in a preset moving average time at a preset sampling interval, the preset moving average time being longer than a sum of the ON-time of the High level,
the microwave generator controls the power of the High level of the pulse-modulated microwave based on the averaged first High measurement value and the set power of High level, and
the microwave generator controls the power of the Low level of the pulse-modulated microwave based on the averaged first Low measurement value and the set power of Low level.

2. The microwave output device of claim 1 , further comprising:
a second directional coupler configured to output a part of a reflection wave returned back to the output unit,
wherein the measurer determines a second High measurement value and a second Low measurement value respectively indicating a High level and a Low level of a power of the reflection wave in the output unit, based on the part of the reflection wave outputted from the second directional coupler,
the microwave generator averages the second High measurement value and the second Low measurement value in a preset moving average time at a preset sampling interval, the preset moving average time being longer than a sum of an ON-time of the High level,
the microwave generator controls the power of the High level of the pulse-modulated microwave based on the averaged first High measurement value, the averaged second High measurement value, and the set power of High level, and
the microwave generator controls the power of the Low level of the pulse-modulated microwave based on the averaged first Low measurement value, the averaged second Low measurement value, and the set power of Low level.

3. The microwave output device of claim 1 ,
wherein the preset moving average time is longer than a sum of an OFF-time of the Low level.

4. The microwave output device of claim 1 ,
wherein the Low level is zero.

5. A plasma processing apparatus, comprising:
a chamber main body; and
a microwave output device as claimed in claim 1 , the microwave output device being configured to output a microwave for exciting a gas supplied into the chamber main body.

Assignees

• Tokyo Electron Ltd
• Tokyo Keiki Inc

Inventors

• Ishida Yohei
• Kaneko Kazushi
• Tamura Hajime
• Murai Koichi

Classifications

• H01J37/32275

  Microwave reflectors · CPC title

• H01J37/32266

  Means for controlling power transmitted to the plasma · CPC title

• H01J37/32935

  Monitoring and controlling tubes by information coming from the object and/or discharge · CPC title

• H01J37/32311 Primary

  Circuits specially adapted for controlling the microwave discharge · CPC title

• H01J37/32302

  Plural frequencies · CPC title