Faraday Shielded Plasma Source for Redeposition Control

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Solution Overview

Problem

The buildup of redeposited material on the chamber walls in plasma processing systems leads to contamination and RF power attenuation, necessitating frequent maintenance, which is costly and disruptive in semiconductor manufacturing.

Innovation Solution

A plasma producing apparatus with a Faraday shield and RF power supply that alternates polarity at low frequencies to shield the chamber interior from redeposited material, using a grounded Faraday shield with vertically aligned slots to prevent horizontal eddy currents and alternating RF power to ensure uniform plasma distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If sputter etching is performed to remove material from substrate surface, then material removal and interface quality are improved, but redeposited material accumulates on chamber walls causing contamination and RF power attenuation

Engineering Contradiction:

Improveinterface qualityVSAvoidredeposited material accumulation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

A Faraday shield is introduced as an intermediary component between the substrate and chamber walls. The shield captures redeposited material before it reaches the chamber walls, preventing contamination and RF power attenuation while allowing the sputter etching process to continue effectively

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of ion bombardment (which causes material sputtering and redeposition) into a beneficial cleaning mechanism. By applying RF power with alternating polarity to the Faraday shield, ions are attracted to and bombard the shield surface, sputtering away redeposited material and preventing accumulation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If maintenance cleaning is performed frequently to remove redeposited material, then chamber cleanliness and process reliability are maintained, but production downtime and costs increase

Engineering Contradiction:

Improveprocess reliabilityVSAvoidmaintenance downtime

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The Faraday shield is designed to clean itself through the plasma processing operation. The alternating polarity RF power supply creates ion bombardment that continuously sputters away redeposited material from the shield surface, enabling self-cleaning during normal operation and eliminating the need for frequent manual maintenance

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cleaning action is made continuous rather than periodic. The RF power supply operates continuously during plasma processing, maintaining the Faraday shield in a clean state throughout production runs, thereby eliminating interruptions for maintenance cleaning

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If conductive coating builds up on chamber walls over time, then material removal continues, but RF power attenuation increases and etch uniformity deteriorates

Engineering Contradiction:

Improvematerial removal rateVSAvoidetch uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The Faraday shield acts as an intermediary barrier that prevents conductive material from reaching and coating the chamber walls. By capturing redeposited material on the shield surface instead, the shield protects the chamber walls from building up conductive coatings that would attenuate RF power and compromise etch uniformity

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Extends maintenance intervals, maintains substrate processing repeatability, and improves etch uniformity by effectively preventing redeposition and maintaining etch rate, reducing downtime and costs.

Implementation Method 1

a Faraday shield disposed within the chamber for shielding at least part of the interior surface from material removed from the substrate by the plasma processing

Methodology Applied

Scientific EffectFaraday shield: Faraday Cage

Implementation Method 2

RF power from the coil antenna generates an inductively coupled plasma (ICP)

Methodology Applied

Scientific EffectInductively coupled plasma: Electromagnetic Induction

Implementation Method 3

The Faraday shield may comprise a plurality of apertures. The apertures may be vertically aligned slots... because a continuous horizontal band of metal deposited on the interior surface of the chamber causes eddy current losses

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 4

The resultant ion bombardment etches the surface of the substrate

Methodology Applied

Scientific EffectSputter etching: Sputtering

Data Source

PatentUS12555743B2Plasma producing apparatus

Publication Date: 2026.02.17 SPTS TECH LTD

AI summary

A plasma producing apparatus for plasma processing a substrate Includes a chamber having an interior surface, a plasma production device for producing an inductively coupled plasma within the chamber, a substrate support for supporting the substrate during plasma processing, and a Faraday shield disposed within the chamber for shielding at least part of the interior surface from material removed from the substrate by the plasma processing. The plasma production device includes an antenna and a RF power supply for supplying RF power to the antenna with a polarity which is alternated at a frequency of less than or equal to 1000 Hz.