Shaped Anode and Shield Connection for Plasma Stability

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Solution Overview

Problem

In radio frequency sputtering physical vapor deposition, plasma instability and unintended deposition on chamber walls occur due to plasma spreading and reversal of deposition mode, affecting the properties and stability of the thin film.

Innovation Solution

The design includes an extended anode with an annular flange and an electrically conductive strap connecting the anode to the shield, increasing the anode's surface area and grounding the shield to the anode's potential, which stabilizes the plasma and reduces plasma spill-out and unintended deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the anode surface area is increased to stabilize plasma, then plasma stability improves, but device complexity increases

Engineering Contradiction:

Improveplasma stabilityVSAvoidanode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The anode is segmented into a body portion and a flange portion, where the flange extends radially outward to increase surface area. This segmentation allows the anode to provide both plasma stability through increased area and structural simplicity through a modular design that separates functional regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The anode transitions from a simple planar structure to a three-dimensional structure with a flange extending in the radial dimension. This dimensional change increases the effective surface area for plasma interaction without significantly increasing the vertical height or complicating the mounting structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the shield is electrically connected to the anode to reduce plasma spill-out, then deposition uniformity improves, but device complexity increases

Engineering Contradiction:

Improvedeposition uniformityVSAvoidelectrical connection structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The shield is electrically connected to the anode through a conductive path, merging their electrical potentials. This combination ensures that the shield and anode work together to contain plasma within the discharge region, improving deposition uniformity while using a straightforward electrical connection rather than a complex isolation system.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the annular flange projects inwardly to define plasma generation volume, then plasma confinement improves, but manufacturing complexity increases

Engineering Contradiction:

Improveplasma confinementVSAvoidanode fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 the stability of the deposition process by containing plasma within the intended discharge space, improving deposition uniformity and reducing target material deposition on chamber walls.

Implementation Method 1

When the RF power is initiated, a plasma is formed

Methodology Applied

Scientific EffectPlasma generation: Plasma

Implementation Method 2

Positive gas ions are pulled to the target surface

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

an electrically conductive body connecting the anode and the shield can reduce the spill-out of plasma

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

The annular flange is positioned to define a volume below the target for the generation of plasma

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS8066857B2Shaped anode and anode-shield connection for vacuum physical vapor deposition

Publication Date: 2011.11.29 FUJIFILM CORP

AI summary

A physical vapor deposition apparatus includes a vacuum chamber with side walls, a cathode, a radio frequency power supply, a substrate support, a shield, and an anode. The cathode is inside the vacuum chamber, and the cathode includes a sputtering target. The radio frequency power supply is configured to apply power to the cathode. The substrate support is inside and electrically isolated from the side walls of the vacuum chamber. The shield is inside and electrically connected to the side walls of the vacuum chamber. The anode is inside and electrically connected to the side walls of the vacuum chamber. The anode includes an annular body and an annular flange projecting inwardly from the annular body, and the annular flange is positioned to define a volume below the target for the generation of plasma.