Plasma Processing Apparatus Multi-Frequency Carrier Wave Control

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Solution Overview

Problem

Existing plasma processing apparatuses face difficulties in efficiently absorbing power from a carrier wave group with multiple frequencies into plasma, due to reflection waves, which reduces the absorption efficiency.

Innovation Solution

A plasma processing apparatus that generates a carrier wave group with multiple frequencies, includes a spectrum detecting unit to analyze progressive and reflection wave spectra, and a control unit that adjusts parameters such as center frequency or tuner positions to maximize absorption power above a threshold value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a carrier wave group including multiple carrier waves having different frequencies is used instead of a single frequency microwave, then the adaptability to different usage conditions is improved, but the power absorption efficiency into plasma deteriorates

Engineering Contradiction:

Improveadaptability to usage conditionsVSAvoidpower absorption efficiency

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by adjusting the frequency distribution and spectral characteristics of the carrier wave group. The control unit modifies parameters such as center frequency, frequency spacing, and spectral shape to optimize power absorption efficiency while maintaining adaptability to different plasma processing conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by detecting the reflection wave spectrum and using this information to adjust the carrier wave group parameters. The spectrum detecting unit monitors the plasma coupling condition, and the control unit dynamically adjusts the frequency characteristics of the carrier wave group to maximize power absorption efficiency based on real-time feedback.

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If a tuner for impedance matching is used to minimize reflection wave power, then the power absorption efficiency is improved, but the device complexity increases

Engineering Contradiction:

Improvepower absorption efficiencyVSAvoiddevice complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical tuner system with a control system that adjusts the frequency characteristics of the carrier wave group. Instead of physically adjusting impedance matching components, the system uses spectral control of the microwave source to achieve optimal power transfer, thereby reducing mechanical complexity while maintaining or improving power absorption efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the microwave source (frequency distribution, spectral shape) to achieve impedance matching effects without requiring physical tuner adjustments. By modifying the frequency domain characteristics of the carrier wave group, the system achieves optimal power coupling with variable plasma conditions.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for high-efficiency absorption of power from the carrier wave group into plasma, enhancing the plasma processing efficiency by optimizing the absorption power and minimizing reflection waves.

Implementation Method 1

generate a carrier wave group including multiple carrier waves having different frequencies

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

generate plasma within the processing vessel by using the carrier wave group

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

ionizing a processing gas within the processing vessel

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Implementation Method 4

detect a progressive wave spectrum, which is a frequency spectrum of a progressive wave of the carrier wave group, and a reflection wave spectrum

Methodology Applied

Scientific EffectSpectral analysis: Absorption Spectroscopy

Implementation Method 5

adjust a parameter... such that the absorption power becomes equal to or larger than a threshold value

Methodology Applied

Scientific EffectImpedance matching: Reflection

Data Source

PatentUS10622197B2Plasma processing apparatus and plasma processing method

Publication Date: 2020.04.14 TOKYO ELECTRON LTD

AI summary

A plasma processing apparatus includes a processing vessel; a carrier wave group generating unit configured to generate a carrier wave group including multiple carrier waves having different frequencies belonging to a preset frequency band centered on a predetermined center frequency; a plasma generating unit configured to generate plasma by using the carrier wave group; a spectrum detecting unit configured to detect a progressive wave spectrum and a reflection wave spectrum of the carrier wave group; and a control unit configured to calculate, by using the progressive wave spectrum and the reflection wave spectrum, an absorption power which is a power of the carrier wave group absorbed into the plasma, and configured to adjust a parameter, which varies a minimum value of the reflection wave spectrum and a frequency corresponding to the minimum value, such that the absorption power becomes equal to or larger than a threshold value.