Achromatic Beam Deflector Octopole Compensation
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Solution Overview
Problem
Modern semiconductor and charged particle beam technologies face challenges in achieving high resolution and minimizing aberrations due to the introduction of dispersion by beam separator devices, particularly the unbalanced achromatic Wien filter, which impairs spot size and resolution in high-speed Electron Beam Inspection applications.
Innovation Solution
An achromatic beam deflector and separator device design that incorporates both magnetic and electrostatic deflection elements, with at least one element positionable to compensate for octopole influences, ensuring the primary charged particle beam remains on the optical axis while minimizing fourfold aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a beam separator including magnetic deflection fields or a Wien filter element is used to separate secondary and backscattered particles from the primary beam, then particle separation efficiency is improved, but primary beam dispersion is introduced which limits attainable resolution
Solution Approach 1:
The patent extracts and eliminates the harmful octopole field influence from the beam separator system by positioning the electrostatic deflection element to compensate for this specific aberration, thereby removing the resolution-limiting factor while maintaining particle separation capability
Solution Approach 2:
The patent changes the spatial parameters of the deflection elements, specifically positioning the electrostatic deflection element at a distance from the magnetic deflection element, to optimize the balance between separation efficiency and beam resolution by compensating for octopole influences
2Measurement precision
If an unbalanced achromatic Wien filter is used to avoid primary beam dispersion, then beam resolution is improved, but fourfold aberrations are introduced which impair spot size and spot resolution
Solution Approach 1:
The patent converts the harmful octopole field influence into a beneficial compensation mechanism by strategically positioning the electrostatic deflection element to generate an opposing field that cancels out the aberrations, thereby eliminating spot size impairment while maintaining achromatic performance
Solution Approach 2:
The patent applies local field compensation by positioning the electrostatic deflection element at a specific location where it can针对性地 compensate for octopole influences in the critical beam region, creating localized field optimization without affecting overall system architecture
3Measurement precision
If additional correction elements are added to compensate for octopole influences and minimize fourfold aberrations, then imaging resolution is improved, but device complexity increases
Solution Approach 1:
The patent makes the electrostatic deflection element serve multiple functions: it performs both the necessary particle separation task and simultaneously compensates for octopole influences and minimizes fourfold aberrations, thereby improving imaging resolution without adding separate correction elements or increasing device complexity
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 design effectively avoids fourfold aberrations, simplifies the charged particle beam system, and enhances imaging resolution without the need for additional correction elements, enabling high current/high resolution imaging.
Implementation Method 1
a magnetic deflection element adapted to generate a magnetic field
Implementation Method 2
an electrostatic deflection element adapted to generate an electric field overlapping the magnetic field
Implementation Method 3
an electrostatic deflection element adapted to generate an electric field overlapping the magnetic field
Data Source
AI summary
An achromatic beam separator device for separating a primary charged particle beam from another charged particle beam and providing the primary charged particle beam on an optical axis (142) is provided, including a primary charged particle beam inlet (134), a primary charged particle beam outlet (132) encompassing the optical axis, a magnetic deflection element (163) adapted to generate a magnetic field, and an electrostatic deflection element (165) adapted to generate an electric field overlapping the magnetic field, wherein at least one element chosen from the electrostatic deflection element and the magnetic deflection element is positioned and/or positionable to compensate an octopole influence.