Multi-Beam Irradiation Device for Off-Axis Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-beam Scanning Electron Microscopes (SEM) face challenges in correcting off-axis aberrations during high-speed Field Of View (FOV) movement, which limits high-accuracy measurement and inspection capabilities due to the inability to effectively suppress deflection aberrations when multiple beams pass through the lens axis.
Innovation Solution
A beam irradiation device configuration that includes a beam source, an objective lens, a first lens for deflecting beams toward the objective lens's optical axis, a second lens for focusing beams on the first lens, and a third lens for deflecting beams toward the second lens's optical axis, allowing for the correction of off-axis aberrations through a deflection aberration corrector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams pass through off-axis position to enable multi-beam irradiation, then productivity is improved, but off-axis aberration increases causing spot diameter enlargement
Solution Approach 1:
The optical system is segmented into multiple independent lens units (first lens unit, second lens unit, third lens unit) that can be independently adjusted. Each lens unit handles specific beam correction tasks, allowing multiple beams to be irradiated simultaneously while maintaining precise spot diameter control through individual lens adjustments.
2Productivity
If FOV movement is performed at high speed to improve measurement speed, then productivity is improved, but deflection aberration increases reducing measurement accuracy
Solution Approach 1:
The optical system performs preliminary correction of deflection aberration through the configured lens units before beams reach the sample. By pre-correcting the beam paths through the first, second, and third lens units, the system enables high-speed FOV movement while maintaining measurement accuracy, as the aberration correction is built into the optical path configuration.
3Manufacturing precision
If aperture lens shape is adjusted to correct off-axis aberration, then manufacturing precision is improved, but device complexity increases due to feedback control requirements
Solution Approach 1:
The patent replaces complex feedback control mechanisms with a fixed optical configuration. The first, second, and third lens units are positioned and configured to provide inherent off-axis aberration correction through their optical design, eliminating the need for dynamic feedback control systems while maintaining manufacturing precision.
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 enables high-speed, high-accuracy measurement and inspection by correcting off-axis aberrations, allowing for simultaneous beam deflection and FOV movement without degrading resolution, thereby enhancing the speed and precision of multi-beam SEM operations.
Implementation Method 1
a first lens which is arranged such that a lens main surface is positioned at an object point of the objective lens and deflects a plurality of incident beams toward an intersection point of a lens main surface of the objective lens and an optical axis
Implementation Method 2
a second lens which is arranged closer to a beam source side than the first lens and focuses the plurality of beams on a lens main surface of the first lens
Implementation Method 3
a third lens which is arranged closer to the beam source side than the second lens and deflects the plurality of beams toward an intersection point of a lens main surface of the second lens and the optical axis
Implementation Method 4
an objective lens which focuses a beam on a sample
Data Source
AI summary
The present disclosure aims at proposing a multi-beam irradiation device capable of correcting off-axis aberrations. In order to achieve the above object, a beam irradiation device is proposed, which includes a beam source which emits a plurality of beams; an objective lens (17) which focuses a beam on a sample; a first lens (16) which is arranged such that a lens main surface is positioned at an object point of the objective lens and deflects a plurality of incident beams toward an intersection point of a lens main surface of the objective lens and an optical axis; a second lens (15) which is arranged closer to a beam source side than the first lens and focuses the plurality of beams on a lens main surface of the first lens; and a third lens (14) which is arranged closer to the beam source side than the second lens and deflects the plurality of beams toward an intersection point of a lens main surface of the second lens and the optical axis.