Charging Area Ion Guidance in Plasma Coating

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Solution Overview

Problem

In vacuum coating processes, ions from a plasma often miss the substrate and hit secondary surfaces, leading to impurity deposition and undersupply of ions to complex components with undercuts, resulting in incomplete coating and mechanical repositioning requirements.

Innovation Solution

A substrate holder with a charging area and a freely selectable potential is used to redirect ions that have missed the substrate onto the substrate surface, and a secondary surface within the coating system is made chargeable to prevent ions from hitting side surfaces, utilizing a second voltage source and controller to adjust potentials for optimal ion guidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If ions are accelerated towards substrates by applying high voltage, then coating quality is improved, but ions may miss the substrate and hit secondary surfaces causing impurity deposition

Engineering Contradiction:
Improvecoating qualityVSAvoidimpurity deposition
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of ions missing the substrate and hitting secondary surfaces into a beneficial effect by introducing a charging area that captures these stray ions. The charging area, made of insulating material, accumulates positive charge from stray ions, creating an electric field that redirects them onto the substrate surface, thereby converting what was previously a harmful effect (impurity deposition) into a beneficial one (enhanced ion coverage).

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

Solution Approach 2:

The charging area acts as an intermediary between the ion source and the substrate. It captures stray ions that would otherwise hit secondary surfaces and uses the accumulated charge to create an electric field that guides these ions onto the substrate. This intermediary structure resolves the contradiction by intercepting harmful ions and redirecting them beneficially.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If ions are accelerated towards substrates, then coating density is improved, but complex components with undercuts receive insufficient ion coverage

Engineering Contradiction:
Improvecoating uniformityVSAvoidion coverage
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent introduces a new spatial dimension for ion interaction by placing a charging area on the substrate holder that extends into the ion path. This charging area creates an extended electric field region that acts in addition to the direct substrate attraction field, providing enhanced ion guidance particularly for complex geometries with undercuts that are difficult to reach by direct line-of-sight ion bombardment.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If a charging area is provided on the substrate holder, then ion guidance is improved, but system complexity increases

Engineering Contradiction:
Improveion guidanceVSAvoidsubstrate holder structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by making only specific areas of the substrate holder insulating (the charging area) while leaving other areas conductive. This localized modification creates the necessary charge accumulation region without requiring the entire substrate holder to be complex insulating structures, thereby minimizing the increase in overall system complexity.

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 solution enhances ion coverage on the substrate, reducing impurity deposition and eliminating the need for mechanical repositioning of complex components, ensuring a uniform and complete coating without increasing the complexity of the coating system.

Implementation Method 1

A charging area is designed on the surface of the substrate holder so that it can be charged by ions arriving from the ion source of the coating system

Methodology Applied
Scientific EffectIon accumulation and electric field generation: Electrostatics

Implementation Method 2

An electric field emanates from this charge, which on balance reduces the electric field in the free space between the ion source and the substrate holder. So ions from the ion source that miss the substrate become weaker on the Substrate holder accelerated towards.

Methodology Applied
Scientific EffectIon deflection by electric field: Lorentz Force

Implementation Method 3

a second contact is provided via which an electrode area on the surface of the substrate holder can be connected to a Potential UH different, freely selectable potential

Methodology Applied
Scientific EffectElectrostatic field control: Electric Field

Implementation Method 4

The plasma acts as a source of ions of coating material

Methodology Applied
Scientific EffectPlasma generation: Plasma

Implementation Method 5

By applying a high voltage to the individual substrates, ions are accelerated towards the substrates

Methodology Applied
Scientific EffectIon acceleration by voltage: Lorentz Force

Implementation Method 6

For example, an insulating piece of material of the substrate holder can provide the loading area. In particular, the substrate holder can be made entirely of insulating material

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP3491165A1Improved guidance of ions from a plasma to a substrate to be coated
Publication Date: 2019.06.05 ROBERT BOSCH GMBH

AI summary

The invention relates to a substrate holder (1) comprising a first contact (3) for the supply of a potential Us to the substrate (2), a charging region (12) on the surface (11) of the substrate holder (1) being designed such that it can be charged (13) with ions (101, 102) from the ion source (104) of a coating facility (100), and/or a second contact (4) is provided by means of which a freely selectable potential UH different from the potential Us can be applied to an electrode region (14) on the surface (11) of the substrate holder (1). The invention also relates to a coating facility (100) comprising at least one ion source (104) and a first voltage source (106) that can be connected to the substrate to be coated (2) such that gas ions (101) and/or ions (102) of a coating material (103) can be accelerated in the direction of the substrate (2) from the ion source (104) by means of an electric potential Us applied to the substrate (2) from the first voltage source (106), at least one secondary surface (11, 105), towards which ions (101, 102) missing the substrate (2) move, being designed (13, 113) such that it can be charged with arriving ions (101, 102), and/or at least one second voltage source (107) being provided, which can be connected to the secondary surface (11, 105) such that a freely selectable potential Us different from the potential Us can be applied to said secondary surface (11, 105). The invention further relates to an operating method and to a computer program product.