Charged Particle Beam Aberration Correction Lens
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Solution Overview
Problem
Scanning electron microscopes face challenges in maintaining resolution during 3D observations of specimens when electron beams are tilted, as aberrations such as deflected chromatic and coma aberrations increase the beam diameter, and existing techniques struggle to correct these aberrations simultaneously.
Innovation Solution
A charged-particle-beam device incorporating an aberration generation lens and a correction lens, where the correction lens's principal plane is positioned at a crossover point to focus beams regardless of energy and opening angles, allowing for simultaneous correction of aberrations caused by energy and angle differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electron beams are tilted by a deflector for 3D observation, then the ability to make 3D observation is improved, but aberration is generated and beam diameter increases
Solution Approach 1:
An aberration correction lens is introduced as an intermediary component between the deflector and the objective lens. This correction lens specifically addresses the aberrations generated by beam tilting, allowing the deflector to function for 3D observation while the correction lens compensates for the resulting beam diameter increase and resolution deterioration.
Solution Approach 2:
The patent adjusts optical parameters by positioning the principal plane of the correction lens at a specific crossover position where beams with different opening angles converge. This parameter optimization enables effective correction of aberrations including high-order chromatic aberration, allowing beam tilting without significant loss of resolution.
2Adaptability or versatility
If electron beams are tilted at larger angles for enhanced 3D imaging, then the 3D imaging capability is improved, but multiple aberrations stand out and resolution deteriorates remarkably
Solution Approach 1:
The aberration correction lens serves as a dedicated intermediary that specifically targets and corrects the multiple aberrations (deflected chromatic aberration, deflected coma aberration, and high-order chromatic aberration) that become prominent at larger tilting angles, thereby preserving resolution during enhanced 3D imaging.
Solution Approach 2:
The correction lens is positioned to preemptively counteract the aberrations before they significantly degrade the image quality. By placing the principal plane at the crossover position, the system proactively corrects beam trajectories with different opening angles, preventing resolution deterioration before it occurs during large-angle tilting for 3D imaging.
3Manufacturing precision
If a correction lens is added to prevent high-order chromatic aberration, then aberration correction is improved, but device complexity increases
Solution Approach 1:
The correction lens is designed to perform multiple functions simultaneously: it corrects high-order chromatic aberration, deflected chromatic aberration, and deflected coma aberration. By consolidating multiple correction functions into a single lens component, the patent improves aberration correction without proportionally increasing device complexity.
Solution Approach 2:
The patent combines the aberration correction function with the existing optical path by integrating the correction lens at a strategic location where it can address multiple aberration types simultaneously. This merging approach allows comprehensive aberration correction while minimizing the increase in overall system 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 configuration effectively restricts resolution deterioration even when beams are largely deflected, enabling precise 3D imaging by canceling multiple aberrations and maintaining high resolution.
Implementation Method 1
a correction lens for focusing trajectories of the charged-particle beams on the principal plane of an objective lens irrespective of energy of the charged-particle beams
Implementation Method 2
an aberration generation lens for generating an aberration when charged-particle beams pass off the axis
Data Source
AI summary
Provided is a charged-particle-beam device capable of simultaneously cancelling out a plurality of aberrations caused by non-uniform distribution of the opening angle and energy of a charged particle beam. The charged-particle-beam device is provided with an aberration generation lens for generating an aberration due to the charged particle beam passing off-axis, and a corrective lens for causing the trajectory of the charged particle beam to converge on the main surface of an objective lens irrespective of the energy of the charged particle beam. The main surface of the corrective lens is disposed at a crossover position at which a plurality of charged particle beams having differing opening angles converge after passing through the aberration generation lens.