Objective Lens Array Apertures for Off-Axis Multi-Beam Focusing
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Solution Overview
Problem
Current charged-particle tools, such as SEMs, face challenges in improving throughput and accuracy due to off-axis aberrations in multi-beam systems, which affect the inspection and detection of micro and nano-scale defects on semiconductor substrates, leading to reduced yield and increased production costs.
Innovation Solution
An electron-optical apparatus with an objective lens array assembly that compensates for off-axis aberrations by using planar elements with apertures of varying sizes and positions, aligned along sub-beam paths, to focus a multi-beam of charged particles effectively on a sample, enhancing the focusing capabilities and reducing aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-beam system is used to increase throughput, then productivity is improved, but off-axis aberrations worsen manufacturing precision
Solution Approach 1:
The patent applies local quality by making each aperture in the planar elements have a specifically tailored size and shape that is optimized for its particular position in the multi-beam array. Off-axis apertures have different dimensions compared to on-axis apertures, allowing each beam to be corrected for its specific aberrations while maintaining high throughput with multiple beams
Solution Approach 2:
The patent changes the geometric parameters of the apertures (size, shape, position) in the planar elements to compensate for off-axis aberrations. By varying the aperture parameters across the array, the system maintains focusing precision for all beams simultaneously, enabling high-productivity multi-beam operation without sacrificing manufacturing precision
2Manufacturing precision
If apertures with varying sizes are used to compensate for off-axis aberrations, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the beam correction function into multiple discrete apertures arranged in planar elements. Each aperture is a simple geometric feature, but the collective arrangement of many segmented apertures achieves the complex function of correcting off-axis aberrations across the entire multi-beam array
Solution Approach 2:
The patent uses multiple identical planar element structures that are replicated and arranged in an array. Each planar element contains apertures that are copies of a basic design, but positioned and sized to address specific aberrations for different beams. This copying approach simplifies manufacturing while achieving the required 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 solution improves the focusing precision and throughput of charged-particle tools, enabling more accurate detection and inspection of defects, thereby increasing the yield and reducing production costs in semiconductor manufacturing.
Implementation Method 1
an objective lens array configured to project the multi-beam towards a sample
Implementation Method 2
the apertures of one or more of the planar elements are configured to compensate for off-axis aberrations in the multi-beam
Data Source
AI summary
Objective lens array assemblies and associated methods are disclosed. In one arrangement, the objective lens array assembly focuses a multi-beam of sub-beams on a sample. Planar elements define a plurality of apertures aligned along sub-beam paths. An objective lens array projects the multi-beam towards a sample. Apertures of one or more of the planar elements compensate for off-axis aberrations in the multi-beam.