Charged Particle Beam Deflector with Rotation-Free Lens
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Solution Overview
Problem
Charged particle beam devices, such as SEMs, face limitations in resolution due to aberrations and spatial dispersion caused by beam deflector devices, particularly at low energies, which hinder high spatial resolution imaging in the sub-nanometer range.
Innovation Solution
A charged particle beam device with a beam deflector system comprising a first and second magnetic deflector, and a rotation-free electrostatic lens positioned between them to create a crossover, compensating for dispersion and maintaining beam shape, allowing for a deflection angle of up to 90° without introducing substantial aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam deflectors are used to deflect the charged particle beam, then the beam direction can be changed, but spatial dispersion and beam distortion are introduced which deteriorate imaging resolution
Solution Approach 1:
The beam deflection system is segmented into multiple deflectors (first and second deflectors) with a rotation-free lens positioned between them. Each deflector handles a portion of the total deflection angle, and the intermediate lens compensates for dispersion introduced by the first deflector before the beam enters the second deflector. This segmentation allows beam direction control while managing and reducing spatial dispersion effects.
Solution Approach 2:
A rotation-free lens is introduced as an intermediary element between the first and second deflectors. This lens specifically compensates for the spatial dispersion introduced by the first deflector, acting as a mediator that corrects beam distortion before the beam undergoes further deflection. The intermediary lens enables the system to achieve beam direction change while maintaining beam quality and minimizing imaging resolution deterioration.
2Adaptability or versatility
If traditional beam deflectors are used, then beam deflection is achieved, but chromatic and spherical aberrations limit the achievable resolution
Solution Approach 1:
The rotation-free lens is positioned at a specific location (crossover position) between the deflectors where it can locally correct chromatic and spherical aberrations. By placing the lens at this critical position, the system achieves local quality improvement in beam correction without compromising the overall deflection capability. The lens specifically targets and corrects aberrations at the crossover point, maintaining high resolution while preserving beam deflection functionality.
3Ease of operation
If beam deflectors are introduced in the beam path, then beam steering is enabled, but additional aberrations are caused which reduce spatial resolution
Solution Approach 1:
The rotation-free lens serves as an intermediary correction element between the deflectors, specifically designed to compensate for aberrations introduced by the beam steering operation. This intermediary component enables the system to maintain ease of beam steering while simultaneously correcting the additional aberrations that would otherwise reduce spatial resolution.
Solution Approach 2:
The system replaces pure mechanical beam steering with a combined magnetic/electrical deflection system augmented by a rotation-free lens. This substitution allows for more precise control and correction of beam properties, enabling beam steering functionality while maintaining or improving spatial resolution through the lens-based aberration compensation.
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 improves the resolution of charged particle beam devices by minimizing beam distortions and spatial dispersion, enabling high spatial resolution imaging even at low energies, and maintaining the original beam shape, thus overcoming the limitations imposed by traditional beam deflector systems.
Implementation Method 1
a first deflector providing a first magnetic deflection field for deflecting the charged particle beam by a first half of a deflection angle
Implementation Method 2
a second deflector providing a second magnetic deflection field for deflecting the charged particle beam by a second half of a deflection angle
Implementation Method 3
a rotation-free lens, particularly an electrostatic lens, arranged between the first deflector and the second deflector for at least partially compensating for a dispersion of the charged particle beam
Data Source
AI summary
A charged particle beam device (100) is described. The charged particle beam device includes a beam source (150) for generating a charged particle beam (101); a lens device (160); and a beam deflector device (110) for deflecting the charged particle beam with respect to a direction of incidence (A). The beam deflector device includes: a first deflector (112) providing a first magnetic deflection field (B1) for deflecting the charged particle beam by a first half of a deflection angle (α); a second deflector (114) providing a second magnetic deflection field (B2) for deflecting the charged particle beam by a second half of the deflection angle (α); and a rotation-free lens arranged between the first deflector (112) and the second deflector (114) for at least partially compensating for a dispersion introduced by at least one of the first deflector and the second deflector, wherein the lens device (160) is configured for creating a crossover (X) of the charged particle beam at the position of the rotation-free lens.