Hexapole SEM Aberration Corrector for Compact Cs Correction
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Solution Overview
Problem
The high cost and complexity of existing Cs-corrector systems for scanning electron microscopes (SEMs) due to their intricate designs and manufacturing challenges, making them unaffordable for many users, while current solutions fail to effectively correct spherical aberrations at higher opening angles.
Innovation Solution
A compact corrector system using a strong hexapole and a weak hexapole, positioned to generate specific aberrations that combine to correct A2, C3, and D4 aberrations at the sample plane, with split multipoles and precise voltage control, allowing for improved resolution and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional Cs-corrector designs with many additional component elements are used, then spherical aberration correction capability is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The corrector system is divided into multiple multipole elements (first multipole element, second multipole element, and third multipole element) that can be manufactured separately and then assembled. Each element handles specific aberration correction functions, allowing for simplified individual manufacturing while achieving comprehensive correction when combined.
Solution Approach 2:
The multipole elements are designed to serve multiple functions: correcting spherical aberration, correcting astigmatism, and controlling beam positioning. This multi-functionality reduces the need for separate dedicated components for each correction type, thereby reducing overall device complexity.
2Manufacturing precision
If traditional Cs-corrector designs with many additional component elements are used, then spherical aberration correction capability is improved, but manufacturing cost increases significantly
Solution Approach 1:
By segmenting the corrector into fewer, more versatile multipole elements rather than many specialized components, the manufacturing process is simplified. Each multipole element can be manufactured using standard techniques and then assembled, reducing overall manufacturing cost while maintaining correction capability.
Solution Approach 2:
The system uses adjustable voltage parameters applied to the multipole elements to achieve different correction levels and configurations. This parameter-based control allows for flexible optimization of correction performance without requiring additional physical components, thereby reducing manufacturing cost.
3Productivity
If higher opening angles are used in round lenses, then probe current increases, but positive spherical aberration coefficient increases and restricts resolution
Solution Approach 1:
The system converts the harmful effect of positive spherical aberration (which increases with higher opening angles) into a beneficial correction opportunity. By strategically positioning and configuring multipole elements, the aberrations generated at higher opening angles are measured and corrected, allowing the system to exploit higher opening angles for increased probe current while maintaining resolution through active correction.
Solution Approach 2:
The corrector dynamically adjusts the strength and configuration of multipole fields to compensate for spherical aberration variations that occur at different opening angles. This parameter control allows the system to operate at optimal opening angles for maximum probe current while maintaining resolution through real-time aberration correction.
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 compact corrector system enhances the resolution of charged particle microscopes by up to 2.5 times, making high-resolution imaging more accessible and cost-effective by simplifying the design and using accurate fabrication techniques like MEMS technology.
Implementation Method 1
a first multipole element (e.g., a 6-pole element, an 8-pole element, a 12-pole element, etc.) configured to generate a strong hexapole field when a first voltage is applied to it
Implementation Method 2
a second multipole element configured to generate a weak hexapole field that is positioned between the first multipole element and a sample when the corrector module is used in the charged particle microscopy system... when a second voltage is applied to the second multipole element the weak hexapole field it generates applies at least a combination A2 aberration and a combination D4 aberration
Implementation Method 3
the net combination of the aberrations applied to the charged particle beam by the weak and strong hexapole fields result in the beam having a desired A2, C3, and D4 aberrations at or near the sample plane
Data Source
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AI summary
Compact correctors for correcting spherical aberrations of a particle-optical lens in a charged particle microscope system, according to the present disclosure a strong hexapole configured to generate a strong hexapole field when a voltage is applied to it, and a weak hexapole positioned between the strong hexapole and a sample. The strong hexapole is positioned such that the crossover of a charged particle beam of the charged particle system does not pass through the center of the strong hexapole, such that the strong hexapole field applies at least an A2 aberration and a D4 aberration to the charged particle beam. The weak hexapole is further positioned or otherwise configured such that, when a voltage is applied to the weak hexapole it generates a weak hexapole field that applies at least a combination A2 aberration and a combination D4 aberration to the charged particle beam of the charged particle microscopy system.