Electron Optical Column With Dispersion Compensation for Probe Focus

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Solution Overview

Problem

The dispersion generated by beam separators in charged particle beam microscopes deforms the probe spots, leading to reduced resolution in reconstructed images of semiconductor wafers, especially in single-beam and multi-beam apparatuses.

Innovation Solution

An electron optical column is designed with a beam separator and a dispersion device configured to compensate for dispersion, using a combination of electrostatic and magnetic deflectors to maintain a fixed deflection angle and correct for dispersion induced by the beam separator, driven by common power supplies to stabilize the system against voltage fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a beam separator is used to separate secondary electrons from primary electrons, then the detector can be placed off-axis improving detection efficiency, but the beam separator generates dispersion that deforms probe spots and deteriorates image resolution

Engineering Contradiction:

Improvedetection efficiencyVSAvoidimage resolution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

A dispersion device is introduced upstream of the beam separator to generate dispersion in the opposite direction to that generated by the beam separator. This preliminary anti-action compensates for the probe spot deformation and maintains image resolution while allowing the beam separator to function for separating electron beams.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The dispersion device acts as an intermediary element between the electron source and the beam separator. It mediates the beam properties by pre-compensating dispersion effects, enabling the beam separator to separate beams without degrading the final probe spot quality at the sample.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If separate power supplies are used for the beam separator and dispersion device, then each component can be independently controlled, but voltage fluctuations cause focus instability and resolution deterioration

Engineering Contradiction:

Improveindependent controlVSAvoidfocus stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The power supplies for the beam separator and dispersion device are merged into a common power supply system. This ensures that both components receive voltage with the same stability characteristics, preventing relative focus shifts that would occur with independent power supplies having different voltage fluctuations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electrical characteristics of the power supplies are made homogeneous by using a common power source. This homogeneity ensures that voltage fluctuations affect both the beam separator and dispersion device equally, maintaining the compensatory relationship between their dispersion effects and stabilizing the overall beam focus.

Inventive Principle:

Principle #33Homogeneity

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

The solution maintains high resolution by ensuring focused probe spots on the sample, reducing image deterioration caused by dispersion, and stabilizing the focus against power fluctuations, thereby enhancing the imaging quality in charged particle beam microscopes.

Implementation Method 1

The beam separator comprises at least one magnetic deflector and therefore generates dispersion on the one or more primary beams and the one or more secondary beams

Methodology Applied

Scientific EffectMagnetic deflection: Lorentz Force

Implementation Method 2

A dispersion device upbeam from the beam separator, the dispersion device being configured to compensate for dispersion induced in the primary beam by the beam separator

Methodology Applied

Scientific EffectElectrostatic deflection: Electric Field

Implementation Method 3

using a combination of electrostatic and magnetic deflectors to maintain a fixed deflection angle and correct for dispersion induced by the beam separator

Methodology Applied

Scientific EffectMagnetic deflection: Magnetic Field

Data Source

PatentUS12573581B2Electron optical column and method for directing a beam of primary electrons onto a sample

Publication Date: 2026.03.10 ASML NETHERLANDS BV

AI summary

Apparatus and methods for directing a beam of primary electrons along a primary beam path onto a sample are disclosed. In one arrangement, a beam separator diverts away from the primary beam path a beam of secondary electrons emitted from the sample along the primary beam path. A dispersion device is upbeam from the beam separator. The dispersion device compensates for dispersion induced in the primary beam by the beam separator. One or more common power supplies drive both the beam separator and the dispersion device.