Electronically-Variable Immersion Lens for Electron Beam Apparatus

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Solution Overview

Problem

Conventional electrostatic immersion lenses in electron beam apparatuses lack flexibility to operate optimally over a wide range of landing energies, surface fields, and fields of view due to fixed electrode geometry, requiring mechanical changes for different conditions, which is cumbersome and introduces delays.

Innovation Solution

An electronically-variable electrostatic immersion lens with independently-controlled multiple bottom electrodes, allowing voltage ratios to be adjusted electronically to optimize electron-optical effects without mechanical changes, enabling operation across a wider range of conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional electrostatic immersion lenses use fixed electrode geometry, then the lens structure is simple, but the operational flexibility and adaptability to different conditions (landing energies, surface fields, fields of view) are limited

Engineering Contradiction:

Improveoperational flexibilityVSAvoidelectrode configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The bottom electrode is divided into multiple independently controlled segments (first bottom electrode and second bottom electrode), allowing each segment to be controlled separately to achieve different electrostatic field configurations for various operating conditions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The lens transitions from fixed electrode geometry to dynamically adjustable electrode voltages, enabling real-time electronic variation of the electrostatic field to adapt to different landing energies, surface fields, and fields of view without mechanical changes

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If mechanical changes are made to adjust the lens for different conditions, then the lens can adapt to various operating parameters, but the process is cumbersome and introduces delays

Engineering Contradiction:

Improveadjustment capabilityVSAvoidadjustment time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces mechanical adjustment mechanisms with electronic voltage control of the electrode segments, allowing rapid and convenient adjustment of the electrostatic field parameters without physical manipulation of the lens components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If a single voltage is applied to the bottom electrode, then the electrode structure is simple, but the ability to optimize electron-optical effects across a wide range of conditions is reduced

Engineering Contradiction:

Improvevoltage control flexibilityVSAvoidvoltage control system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The bottom electrode is segmented into multiple independently controllable parts, allowing different voltages to be applied to each segment to create optimized electrostatic field distributions for various operating conditions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes independent voltage control of electrode segments to change the electrostatic field parameters dynamically, enabling optimization of electron-optical effects for different landing energies, surface fields, and fields of view

Inventive Principle:

Principle #35Parameter changes

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 operational flexibility, increases defect image contrast and detectability, and provides energy filtering to reject secondary electrons, improving the electron beam apparatus's performance and usability in semiconductor inspection and metrology.

Implementation Method 1

The electrostatic immersion lens includes a top electrode configured with a first voltage applied thereto, an upper bottom electrode configured with a second voltage applied thereto, and a lower bottom electrode configured with a third voltage applied thereto

Methodology Applied

Scientific EffectElectrostatic field: Electric Field

Implementation Method 2

Methodology Applied

Scientific EffectElectrostatic lens focusing: Electrostatic Lens

Implementation Method 3

provides energy filtering to reject secondary electrons

Methodology Applied

Scientific EffectEnergy filtering: Filter (physical)

Data Source

PatentUS7446320B1Electronically-variable immersion electrostatic lens

Publication Date: 2008.11.04 KLA TENCOR TECHNOLOGY CORP

AI summary

One embodiment relates to an electronically-variable electrostatic immersion lens in an electron beam apparatus. The electrostatic immersion lens includes a top electrode configured with a first voltage applied thereto, an upper bottom electrode configured with a second voltage applied thereto, and a lower bottom electrode configured with a third voltage applied thereto. The third voltage is controlled separately from the second voltage. Other embodiments are also disclosed.