Charged Particle Beam Apparatus UV Charge Neutralization

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Solution Overview

Problem

Residual electrical charges on electrostatic chucks in charged particle beam apparatuses, such as electron microscopes, cause focusing issues and adsorption forces, which can lower throughput and lead to conveying errors, and existing methods like direct ultraviolet light irradiation either fail to completely remove charges or damage equipment.

Innovation Solution

A charged particle beam apparatus with an ultraviolet light source that irradiates ultraviolet light perpendicular to the electrostatic chuck, using a shielding plate to prevent direct irradiation and allow dissociated residual gas ions and electrons to neutralize charges, ensuring efficient and uniform charge removal without emitting positive charges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ultraviolet light is directly irradiated onto the electrostatic chuck to remove electrical charges, then charge removal effect is improved, but positive charges are emitted and equipment damage occurs

Engineering Contradiction:

Improveelectrical charge removal effectVSAvoidpositive charge emission

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary substance (residual gas) between the ultraviolet light source and the electrostatic chuck. The ultraviolet light irradiates the residual gas to generate ions and electrons, which then neutralize the electrical charges on the electrostatic chuck surface indirectly, avoiding direct UV irradiation that causes positive charge emission

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the direct optical action (UV light directly on chuck) with a chemical/physical process substitution (UV light ionizing residual gas, then ions/electrons neutralizing charges). This substitutes a harmful direct mechanical/optical interaction with a controlled indirect chemical/physical process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If ultraviolet light is irradiated at an angle to the electrostatic chuck, then charge removal occurs, but uniformity of charge removal is insufficient

Engineering Contradiction:

Improveelectrical charge removalVSAvoiduniformity of charge removal

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent positions the electrostatic chuck perpendicular to the ultraviolet light irradiation direction, creating a symmetric configuration where the residual gas ions and electrons are uniformly distributed across the chuck surface. This perpendicular arrangement ensures equipotential charge neutralization across the entire chuck surface, achieving uniform charge removal

Inventive Principle:

Principle #12Equipotentiality

3Strength

If the electrostatic chuck surface is covered with high insulation material like ceramic, then insulation properties are improved, but electrical charges are prone to accumulate

Engineering Contradiction:

Improveinsulation propertiesVSAvoidelectrical charge accumulation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful charge accumulation property of high insulation materials into a beneficial feature by using the residual gas ions and electrons (generated by UV irradiation) to actively neutralize the accumulated charges. The insulation material's charge retention capability is transformed from a problem into a controllable feature through active charge management

Inventive Principle:

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

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 effectively and uniformly removes residual electrical charges from electrostatic chucks, maintaining stable operation and high throughput by preventing positive charge emission and minimizing equipment damage, while maintaining a vacuum environment.

Implementation Method 1

irradiating ultraviolet light onto the irradiation target member (3210) generates ionized residual gas

Methodology Applied

Scientific EffectPhotoionisation: Photoionisation

Implementation Method 2

an electrostatic chuck mechanism (3205) that holds the sample (3201) to be irradiated by the charged particle beam

Methodology Applied

Scientific EffectCoulomb force: Coulomb's Law

Data Source

PatentUS9105446B2Charged particle beam apparatus

Publication Date: 2015.08.11 HITACHI HIGH TECH CORP

AI summary

An object of the present invention is to provide a charged particle beam apparatus that effectively removes electrical charges from an electrostatic chuck.In order to achieve the above object, the charged particle beam apparatus of the present invention includes a sample chamber that maintains a space containing an electrostatic chuck mechanism (5) in a vacuum state; and in which the charged particle beam apparatus includes an ultraviolet light source (6) to irradiate ultraviolet light within the sample chamber, and a irradiation target member irradiated by the ultraviolet light; and the irradiation target member is placed perpendicular to the adsorption surface of the electrostatic chuck.