Shielded Multi-Beam Forming Unit for Secondary Radiation Control

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Solution Overview

Problem

Multi-beam charged particle microscopes face challenges due to sensitivity to charging effects and damages caused by scattered charged particles, secondary electrons, and secondary radiation, which affect the performance and longevity of array-optical elements.

Innovation Solution

The implementation of a multi-beam charged particle imaging system with a reduced sensitivity to charging and damage, achieved through the use of a shielding multi-aperture plate and active array-optical elements, which effectively shield scattered charged particles and secondary radiation, and a method of adjusting voltages to manage secondary electrons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a multi-beam generating unit with filter plate and array-optical elements is used to generate multiple charged particle beamlets, then imaging resolution and productivity are improved, but the system becomes highly sensitive to charging effects and damage from secondary radiation

Engineering Contradiction:

Improveimaging speedVSAvoidcharging effects and damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A shielding multi-aperture plate is introduced as an intermediary component between the filter plate and the active array-optical element. This shielding plate absorbs scattered charged particles and secondary radiation before they can reach and damage the sensitive array-optical element, while still allowing the primary beamlets to pass through to the sample.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The beam path is segmented into multiple zones with different functions: the filter plate creates the initial multi-beam pattern, the shielding plate protects downstream components by absorbing harmful radiation, and the active array-optical element performs precise beam control. This segmentation allows each component to optimize its function without interfering with others.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the primary electron beam intensity is increased to improve imaging speed, then productivity increases, but the generation of secondary electrons and radiation increases, causing more charging and damage

Engineering Contradiction:

Improveimaging speedVSAvoidsecondary electrons and radiation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The shielding multi-aperture plate, positioned downstream of the filter plate, captures and absorbs the harmful secondary electrons and radiation generated by the primary beam, converting this harmful byproduct into a protective function that shields the sensitive array-optical elements from damage.

Inventive Principle:

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

3Device complexity

If array-optical elements are placed close to the filter plate to reduce system complexity, then device complexity is reduced, but sensitivity to charging and damage from scattered particles increases

Engineering Contradiction:

Improvesystem complexityVSAvoidperformance stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The shielding multi-aperture plate serves as a protective intermediary positioned between the filter plate and the active array-optical element. It absorbs scattered charged particles and secondary radiation in the space between these components, preventing them from reaching and damaging the array-optical element while maintaining a compact overall system design.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces the impact of scattered charged particles and secondary electrons on the active array-optical elements, thereby enhancing the imaging performance, increasing the lifetime of the multi-beamlet-forming unit, and minimizing charging and damage effects.

Implementation Method 1

a shielding multi-aperture plate... which effectively shield scattered charged particles and secondary radiation

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

One portion of the electrons of the electron beam is incident onto the filter plate and is absorbed there

Methodology Applied

Scientific EffectAbsorption (physical): Absorption (physical)

Implementation Method 3

The primary electron beamlets trigger secondary electrons or backscattered electrons to emanate as secondary electron beamlets from the object

Methodology Applied

Scientific EffectSecondary electron emission: Photoelectric Effect

Data Source

PatentUS20250125115A1Multi-beam system and multi-beam forming unit with reduced sensitivity to secondary radiation

Publication Date: 2025.04.17 CARL ZEISS MULTISEM GMBH

AI summary

A multi-beam charged particle beam system includes a multi-beam forming unit with a lower sensitivity to secondary electrons, scattered charge particles and x-ray radiation. Thereby, a plurality of primary charged particle beamlets can be generated with higher precision and with a longer lifetime of a multi-beam forming unit. The system and method are applicable for an inspection of samples, for example for wafer or mask inspection.