Beam-Limit Aperture Plate Layout for Low-Crosstalk Multi-Beam SEM
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Solution Overview
Problem
Conventional multi-beam SEMs face limitations in imaging resolution due to crosstalk between detection elements, which is caused by secondary electrons from adjacent beams, leading to compromised image quality and defect detection accuracy in inspecting small IC components.
Innovation Solution
A multi-beam apparatus with a beam-limit aperture plate featuring multiple aperture arrays at different heights, allowing the aperture plate to move in the x or y directions to align with varying secondary electron beam radii, thereby mitigating crosstalk and enhancing imaging resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams are used to increase throughput, then productivity is improved, but crosstalk between detection elements worsens imaging signal fidelity
Solution Approach 1:
The patent divides the aperture plate into multiple aperture arrays positioned at different heights along the optical axis. Each aperture array corresponds to a specific beam and can be independently positioned to control the beam's spatial profile. This segmentation allows simultaneous operation of multiple beams while maintaining individual beam integrity and reducing crosstalk between adjacent detection elements.
Solution Approach 2:
The patent introduces a vertical dimension (z-axis) by positioning aperture arrays at different heights along the optical axis, rather than only in the lateral plane. This dimensional extension allows the system to control beams at multiple focal planes simultaneously, enabling throughput improvement while maintaining imaging fidelity by preventing lateral crosstalk.
2Measurement precision
If multiple aperture arrays at different heights are used, then crosstalk is reduced and imaging resolution is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple aperture arrays onto a single aperture plate structure, integrating them at different heights along the optical axis. This consolidation allows the system to achieve complex beam control functionality while maintaining a relatively simple overall device architecture, as all aperture arrays are part of one movable plate rather than separate components.
Solution Approach 2:
The aperture plate serves multiple functions simultaneously: it defines beam apertures, controls beam spatial profiles, and enables focal plane selection through its vertical positioning. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite the advanced imaging capabilities.
3Adaptability or versatility
If aperture plate moves in x or y directions to align with varying beam radii, then adaptability is improved, but ease of operation worsens due to precise positioning requirements
Solution Approach 1:
The system employs feedback control where the controller automatically determines the appropriate position of the aperture plate based on detected beam parameters, and actuates the positioning mechanism accordingly. This self-service approach eliminates the need for manual precise positioning by operators, maintaining high adaptability while simplifying operation through automation.
Solution Approach 2:
The system uses a feedback loop where the controller monitors beam characteristics and automatically adjusts the aperture plate position to optimal alignment. This feedback mechanism ensures accurate beam alignment and adaptability to varying conditions without requiring complex manual intervention, thereby maintaining ease of operation despite the precision requirements.
Data Source
AI summary
Systems and methods of enhancing imaging resolution by reducing crosstalk between detection elements of a secondary charged-particle detector in a multi-beam apparatus are disclosed. The multi-beam apparatus may comprise an electro-optical system comprising a beam-limit aperture plate having a surface substantially perpendicular to an optical axis, the beam-limit aperture plate comprising a first aperture at a first distance relative to the surface of the beam-limit aperture plate, and a second aperture at a second distance relative to the surface of the beam-limit aperture plate, the second distance being different from the first distance. The first aperture may be a part of a first set of apertures of the beam-limit aperture plate at the first distance, and the second aperture may be a part of a second set of apertures of the beam-limit aperture plate at the second distance.