Multifocal Magnetron Layout for Plasma Confinement in PVD

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Solution Overview

Problem

Magnetrons used in sputter processing for thin film deposition suffer from fringing fields that cause divergence of fast electrons, leading to inefficient ionization and interference when multiple devices are in proximity.

Innovation Solution

The design incorporates a keeper plate with a specific magnetic field configuration, including an annular magnet array and inner magnets of opposing polarities, to confine plasma electrons and minimize fringing fields, ensuring effective ionization and independent plasma zones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional magnetron designs with annular and inner magnets are used, then plasma confinement is achieved, but fringing fields cause electron divergence and reduce ionization efficiency

Engineering Contradiction:

Improveionization efficiencyVSAvoidfringing field electron divergence

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and eliminates the harmful fringing fields by using a magnetron design where the annular magnet and inner magnet are configured to produce magnetic field lines that are perpendicular to the cathode surface throughout the plasma region. This configuration removes the lateral field components that cause electron divergence, thereby eliminating the harmful effect while preserving plasma confinement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the magnetic field parameter configuration by positioning the inner magnet at a specific radius and adjusting the magnetic field strength ratio between the annular and inner magnets. This parameter optimization ensures that the magnetic field lines remain perpendicular to the cathode, preventing electron divergence and maximizing ionization efficiency.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If multiple magnetron devices are placed in proximity, then processing throughput is increased, but magnetic field interference between devices destabilizes plasma operation

Engineering Contradiction:

Improveprocessing throughputVSAvoidplasma stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent extracts and removes the interfering magnetic field components by configuring the magnetron to produce vertically oriented magnetic field lines that do not extend laterally. This eliminates the magnetic field interference that would otherwise occur between adjacent devices, allowing multiple magnetrons to operate stably in proximity while maintaining high productivity.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If inner magnet size is increased to improve plasma confinement, then electron confinement is enhanced, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveplasma confinementVSAvoidmagnet array configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by concentrating the magnetic field strength variation locally at the inner magnet position rather than throughout the entire magnetron structure. The inner magnet is positioned at a specific radius with optimized field strength to create the necessary plasma confinement zone, while the annular magnet provides the baseline field. This localized approach achieves effective plasma confinement without requiring complex overall device design.

Inventive Principle:

Principle #3Local quality

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 configuration enhances plasma confinement, increases the spatial section for ionization of vapor species, and allows for the placement of multiple devices in proximity without significant interference, improving the uniformity and efficiency of thin film deposition.

Implementation Method 1

The inner top magnet and the annular magnet array and the inner bottom magnet form a magnetic field environment that provides plasma confinement of ionizing electrons

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

causing a gas operative as a reactive gas and sputter gas to become ionized

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

apparatus for physical vapor deposition sputter processing of thin film materials

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS12283470B2Multifocal magnetron design for physical vapor deposition processing on a single cathode

Publication Date: 2025.04.22 INTEVAC INC

AI summary

An apparatus has a keeper plate with a keeper plate outer perimeter. An annular magnet array with an annular magnet array outer perimeter is coincident with the keeper plater outer perimeter. An inner top magnet is positioned on a centerline of a first side of the keeper plate and an inner bottom magnet is positioned on the centerline of a second side of the keeper plate. The inner top magnet is of a first magnetic orientation and the annular magnet array and the inner bottom magnet have a second magnetic orientation opposite the first magnetic orientation to form a magnetic field environment that provides plasma confinement of ionizing electrons which causes a gas operative as a reactive gas and sputter gas to become ionized and subsequently be directed to a target cathode while simultaneously causing the ionization of sputtered species which are dispersed across a substrate.