RF Sputtering Counter Electrode Geometry

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Solution Overview

Problem

In RF sputtering, the larger counter electrode is often undesirably sputtered, especially when its plasma potential exceeds the sputtering threshold, leading to contamination of deposited layers, and existing solutions like magnetic fields complicate the apparatus design.

Innovation Solution

The counter electrode is enhanced by an additional electrically conductive member with parallel surfaces, increasing its surface area and reducing sputtering, while maintaining a compact arrangement within the vacuum chamber, allowing for uniform plasma formation and deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the counter electrode area is increased to reduce sputtering, then sputtering of counter electrode material is reduced, but the apparatus occupies more space within the vacuum chamber

Engineering Contradiction:

Improvesputtering of counter electrode materialVSAvoidspace occupied by counter electrode

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The counter electrode is configured with surfaces arranged in multiple dimensions - specifically, surfaces extending in the vertical direction and surfaces extending in the horizontal direction, creating a three-dimensional electrode structure that maximizes surface area within the available chamber volume

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The additional electrically conductive member is positioned within the vacuum chamber in a nested configuration, with surfaces arranged to utilize the available space efficiently without protruding beyond the chamber boundaries

Inventive Principle:

Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If magnets are added to reduce counter electrode sputtering, then sputtering is reduced, but the apparatus design and manufacture become more complex

Engineering Contradiction:

Improvesputtering of counter electrode materialVSAvoidapparatus design and manufacture

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention replaces the magnetic field approach with an electrical field approach by configuring the counter electrode geometry and applying RF voltage, thereby achieving sputtering reduction without requiring additional magnetic components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts the essential function of reducing counter electrode sputtering from the magnetic field approach and achieves it through electrode geometry configuration and RF field application alone, removing the need for magnets

Inventive Principle:

Principle #2Taking out (Extraction)

3Object-affected harmful factors

If the counter electrode area is increased to reduce sputtering, then sputtering is reduced, but the arrangement of the counter electrode within the vacuum chamber becomes more difficult

Engineering Contradiction:

Improvesputtering of counter electrode materialVSAvoidarrangement of counter electrode

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The counter electrode utilizes vertical space by extending surfaces in the vertical direction, allowing increased surface area without increasing the horizontal footprint, thereby simplifying arrangement within the chamber

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The counter electrode is divided into multiple surfaces arranged at different orientations and positions, with at least two surfaces extending in different directions, allowing flexible arrangement and integration within the vacuum chamber structure

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 effectively reduces sputtering of the counter electrode material, preventing contamination and allowing for uniform deposition onto substrates, while simplifying the apparatus design and maintaining operational flexibility.

Implementation Method 1

a high frequency voltage is applied between the two electrodes, which continuously alternates in respect of polarity

Methodology Applied

Scientific EffectRF electric field: Electric Field

Implementation Method 2

a plasma can be formed between the two electrodes

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 3

the electrode with the smaller electrode surface displays a preferential sputtering effect

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS10224188B2RF sputtering arrangement

Publication Date: 2019.03.05 EVATEC AG

AI summary

Apparatus for sputtering comprises a vacuum chamber defined by at least one side wall, a base and a cover, at least one first electrode having a surface arranged in the vacuum chamber, a counter electrode having a surface arranged in the vacuum chamber and a RF generator. The RF generator is configured to apply a RF electric field across the at least one first electrode and the counter electrode so as to ignite a plasma between the first electrode and the counter electrode. The counter electrode comprises at least a portion of the side wall and/or the base of the vacuum chamber and an additional electrically conductive member. The additional electrically conductive member comprises at least two surfaces arranged generally parallel to one another and spaced at a distance from one another.