In-situ Electrostatic Filter Cleaning via Reverse Ion Sputtering

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Solution Overview

Problem

Ion implantation systems face contamination issues due to deposits building up on beam-line components, particularly on shadowed surfaces that are not effectively cleaned by the ion beam, leading to particulate contamination on wafers and requiring frequent maintenance or replacement.

Innovation Solution

An apparatus with a cleaning ion source generating a plasma between the electrostatic filter and the substrate position, coupled with a voltage supply assembly that applies a negative voltage to electrodes, allowing for in-situ cleaning of components by attracting positive ions to physically sputter or reactively etch deposits on the electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cleaning ion source is positioned in the direct line of sight of the ion beam, then cleaning effectiveness for exposed surfaces is improved, but shadowed surfaces remain uncleaned and continue to flake

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidparticulate contamination from shadowed surfaces

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of positioning the cleaning ion source upstream to clean components in its path, the source is positioned downstream (between the electrostatic filter and substrate) and ions are directed upstream toward the electrostatic filter electrodes. This reverse configuration allows ions to reach shadowed surfaces that face the substrate, enabling cleaning of previously inaccessible areas without requiring component removal or repositioning.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If beamline components are removed for cleaning or replacement, then contamination is reduced, but system downtime and maintenance costs increase

Engineering Contradiction:

Improvecomponent cleanlinessVSAvoidmaintenance downtime

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The electrostatic filter electrodes are equipped with voltage supply assemblies that can generate negative potentials to attract and accumulate ions from the cleaning ion source directly onto the electrode surfaces. This self-service capability allows the electrodes to clean themselves in-situ without requiring removal from the system, eliminating maintenance downtime while maintaining component cleanliness through automated ion accumulation and sputtering processes.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cleaning ion source continuously generates ions that are directed to accumulate on electrostatic filter electrodes during normal operation. By performing preliminary cleaning action before contamination becomes severe, the system prevents buildup that would otherwise require shutdown for maintenance, thereby reducing overall downtime while maintaining component cleanliness through proactive ion accumulation.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If ion beam power is increased to improve cleaning, then cleaning effectiveness improves, but damage to the cleaning ion source and increased energy consumption occur

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidenergy consumption and source damage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Negative voltage is applied selectively to specific electrostatic filter electrodes that require cleaning, rather than uniformly to all components. This localized approach concentrates ion flux only where contamination exists on electrode surfaces, maximizing cleaning effectiveness while minimizing total ion generation requirements, thereby reducing energy consumption and preventing damage to the cleaning ion source from excessive power levels.

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

Enables continuous operation with reduced downtime and maintenance costs by effectively cleaning shadowed surfaces within the ion beam apparatus, ensuring cleaner ion beams and minimizing particulate contamination on wafers.

Implementation Method 1

a cleaning ion source generating a plasma between the electrostatic filter and the substrate position

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

a voltage supply assembly that applies a negative voltage to electrodes, allowing for in-situ cleaning of components by attracting positive ions

Methodology Applied

Scientific EffectIon attraction: Ion Repulsion/Attraction

Implementation Method 3

attracting positive ions to physically sputter or reactively etch deposits on the electrodes

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS9761410B2Apparatus and method for in-situ cleaning in ion beam apparatus

Publication Date: 2017.09.12 VARIAN SEMICON EQUIP ASSC INC

AI summary

An apparatus may include an electrostatic filter having a plurality of electrodes; a voltage supply assembly coupled to the plurality of electrodes; a cleaning ion source disposed between the electrostatic filter and a substrate position, the cleaning ion source generating a plasma during a cleaning mode, wherein a dose of ions exit the cleaning ion source; and a controller having a first component to generate a control signal for controlling the voltage supply assembly, wherein a negative voltage is applied to at least one of the plurality of electrodes when the plasma is generated.