RF Termination Filter for Stable Plasma Confinement in Process Chambers

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Solution Overview

Problem

In semiconductor process chambers, the buildup of dielectric material on shielding creates a high impedance path for RF, leading to leaked plasma, reduced plasma density, and potential damage to chamber components.

Innovation Solution

An apparatus with a DC filter and an RF termination filter is used to control RF current in the process chamber, providing a low impedance path and adjusting the impedance of electrodes relative to RF ground to maintain stable plasma confinement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dielectric material builds up on chamber shielding, then RF impedance increases, but RF current seeks alternative paths causing plasma leakage and reduced plasma density

Engineering Contradiction:

Improveplasma confinement stabilityVSAvoidplasma leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An RF termination filter is introduced as an intermediary component between the DC power supply and RF ground. This filter provides a controlled low-impedance path for RF current, mediating the conflict between the high impedance created by dielectric buildup and the need for stable plasma confinement. The filter prevents RF current from seeking harmful alternative paths while maintaining proper plasma density.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If dielectric material builds up on chamber shielding, then RF impedance increases, but chamber components may be damaged

Engineering Contradiction:

Improvechamber component longevityVSAvoidcomponent damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The RF termination filter serves as a protective intermediary that controls RF current flow. By providing a designated low-impedance path through the filter, it prevents RF current from damaging chamber components while accommodating the impedance changes caused by dielectric buildup on shielding.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If RF termination filter is added to control impedance, then plasma confinement is maintained, but device complexity increases

Engineering Contradiction:

Improveplasma confinement stabilityVSAvoidRF circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The RF termination filter is designed to perform multiple functions simultaneously: it controls RF impedance, filters DC current, and provides a stable reference for plasma confinement. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while maintaining plasma confinement stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution effectively reduces RF heating of EMI filters, prevents plasma leakage, and maintains high plasma density within the processing volume, thereby enhancing film quality and chamber component longevity.

Implementation Method 1

a DC filter configured to be electrically connected between a DC power supply and at least one electrode embedded in an electrostatic chuck, the DC filter configured to block DC current from the DC power supply from flowing through the DC filter

Methodology Applied

Scientific EffectElectrical filtering: Filter (electronic)

Implementation Method 2

an RF termination filter configured to be electrically connected between the DC filter and an RF ground of the process chamber where the RF termination filter is configured to adjust an impedance of the at least one electrode relative to the RF ground

Methodology Applied

Scientific EffectImpedance matching: Filter (electronic)

Implementation Method 3

at least one electrode embedded in an electrostatic chuck

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 4

The plasma sputters target material, not only on the substrate, but also on the process chamber shielding as well

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS12249484B2Methods and apparatus for controlling radio frequency electrode impedances in process chambers

Publication Date: 2025.03.11 APPLIED MATERIALS INC

AI summary

Methods and apparatus for controlling plasma in a process chamber leverage an RF termination filter which provides an RF path to ground. In some embodiments, an apparatus may include a DC filter configured to be electrically connected between a DC power supply and electrodes embedded in an electrostatic chuck where the DC filter is configured to block DC current from the DC power supply from flowing through the DC filter and an RF termination filter configured to be electrically connected between the DC filter and an RF ground of the process chamber where the RF termination filter is configured to adjust an impedance of the electrodes relative to the RF ground.