RF Impedance Matching for Plasma Etching Cable Variations

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Solution Overview

Problem

Existing substrate treating apparatuses face challenges in accurately matching impedance due to cable length and configuration changes, leading to power reflection and decreased etching efficiency, as they fail to account for the total impedance including the cable's impedance, especially when commercial cables of varying lengths are used.

Innovation Solution

The apparatus employs an impedance matching unit with multiple sensors to measure and adjust impedance, performing primary and secondary matching to ensure maximum power transmission by accounting for the cable's impedance, thereby compensating for deviations and maintaining optimal power transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a commercial cable of several tens of meters is used to connect the RF power supply and impedance matching unit, then the equipment can be set up with flexible cable disposition, but the cable inductance changes when the cable is bent or repositioned, making it impossible to accurately evaluate and test the substrate treating apparatus

Engineering Contradiction:

Improvecable disposition flexibilityVSAvoidimpedance measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical cable connection system with an electromagnetic coupling system using magnetic fields. The RF power supply and impedance matching unit are coupled through magnetic fields rather than physical cable connections, eliminating the problem of cable inductance changes while maintaining flexible positioning capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces magnetic fields as an intermediary between the RF power supply and impedance matching unit. This intermediary enables energy and signal transmission without direct cable connections, thereby avoiding the harmful effect of cable inductance variations while maintaining system connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the impedance matching unit and process chamber are attached to each other to minimize impedance change, then the impedance stability is improved, but the device complexity and setup difficulty increase

Engineering Contradiction:

Improveimpedance stabilityVSAvoidequipment configuration complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical attachment system with electromagnetic coupling. Instead of physically attaching the impedance matching unit to the process chamber, the system uses magnetic field coupling to maintain impedance stability while allowing independent positioning and reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If a cable of half wavelength length is selected to reduce interference, then the RF interference is minimized, but the cable length and device configuration become more complex

Engineering Contradiction:

ImproveRF interferenceVSAvoidcable length

Core Design Contradiction:

Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The patent eliminates the cable-based RF transmission system and replaces it with direct electromagnetic coupling. This substitution removes the cable length constraint and half-wavelength requirement, reducing RF interference without the need for specific cable lengths or complex cable routing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 more accurate impedance matching, reducing power reflection, improving etching efficiency, and facilitating easier equipment setup and maintenance by accounting for cable-induced impedance changes, ensuring consistent performance across different configurations.

Implementation Method 1

an RF voltage is applied, and then plasma is formed by accelerated electrons

Methodology Applied

Scientific EffectPlasma generation: Plasma

Implementation Method 2

plasma is formed by accelerated electrons

Methodology Applied

Scientific EffectElectromagnetic energy conversion: Electromagnetic Induction

Implementation Method 3

impedance (ZL(t)=R+jX)) of a load terminal that changes in real time according to the plasma state is measured by a sensor

Methodology Applied

Scientific EffectImpedance measurement: Electrical Resistance

Data Source

PatentUS12051565B2Substrate treating apparatus and impedance matching method

Publication Date: 2024.07.30 SYSTEM ENGINEERING MEGA SOLUTION CO LTD

AI summary

Disclosed is an apparatus for treating a substrate. The apparatus includes: an RF power supply; a process chamber which performs plasma processing by using power applied from the RF power supply; and an impedance matching unit which is disposed between the RF power supply and the process chamber and performs matching, in which the RF power supply includes a first sensor measuring impedance in a direction of the process chamber and the impedance matching unit, and the impedance matching unit performs impedance matching by reflecting impedance measured in the RF power supply through the first sensor.