Multi-Beam Electron Optics for Coulomb-Limited Imaging Resolution
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Solution Overview
Problem
Existing multi-beam charged-particle microscopes face limitations in imaging resolution due to variations in beam current and position, which are exacerbated by Coulomb interaction effects, making defect detection in small IC components challenging.
Innovation Solution
A multi-beam charged-particle microscope with a first aperture array generating primary beamlets and a condenser lens adjusting the position of a second aperture array to generate probing beamlets, mitigating Coulomb effects by using apertures with varying shapes and positions, and a condenser lens to control beam current and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams are used to increase throughput, then productivity is improved, but imaging resolution deteriorates due to limitations in variation of probe current
Solution Approach 1:
The patent divides the electron beam into multiple beamlets using aperture arrays, allowing simultaneous multi-point inspection that increases throughput while maintaining resolution through controlled beamlet parameters
Solution Approach 2:
The patent implements dynamic control of probe current variation across multiple beams, enabling resolution adjustment for different inspection regions while maintaining high throughput through parallel processing
2Reliability
If probe current is increased to improve signal strength, then detection capability is improved, but imaging resolution deteriorates due to Coulomb interaction effects
Solution Approach 1:
The patent applies different aperture configurations and beam current levels to different spatial regions, allowing high current for signal strength where needed while maintaining low current for resolution in critical inspection areas
Solution Approach 2:
The patent dynamically adjusts beam current parameters across multiple beams to optimize the balance between signal strength for defect detection and current density for maintaining imaging resolution
3Productivity
If aperture size is increased to allow more beam current, then productivity is improved, but Coulomb interaction effects worsen, reducing imaging resolution
Solution Approach 1:
The patent segments the aperture into multiple smaller openings that collectively transmit sufficient current while maintaining small individual aperture sizes to minimize Coulomb interaction effects and preserve imaging resolution
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
Enhances imaging resolution and defect detection accuracy by reducing Coulomb interaction effects, allowing for a wide range of beam currents while maintaining mechanical integrity.
Implementation Method 1
a charged-particle source configured to generate a primary charged-particle beam
Implementation Method 2
a condenser lens comprising a plane adjustable along the primary optical axis
Implementation Method 3
a first aperture array comprising a first plurality of apertures configured to generate a plurality of primary beamlets from the primary charged-particle beam
Data Source
AI summary
Systems and methods of mitigating Coulomb effect in a multi-beam apparatus are disclosed. The multi-beam apparatus may include a charged-particle source configured to generate a primary charged-particle beam along a primary optical axis, a first aperture array comprising a first plurality of apertures having shapes and configured to generate a plurality of primary beamlets derived from the primary charged-particle beam, a condenser lens comprising a plane adjustable along the primary optical axis, and a second aperture array comprising a second plurality of apertures configured to generate probing beamlets corresponding to the plurality of beamlets, wherein each of the plurality of probing beamlets comprises a portion of charged particles of a corresponding primary beamlet based on at least a position of the plane of the condenser lens and a characteristic of the second aperture array.