Charged Particle Beam Aberration Correction for 3D Imaging
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Solution Overview
Problem
Charged particle beam columns face challenges in effectively compensating aberrations caused by highly tilted angles of the beam, which distort the beam and prevent a small focus diameter, especially when using scanning electron microscopes to reconstruct three-dimensional structures.
Innovation Solution
Incorporating a deflector and an aberration corrector in the beam path between the condenser lenses and the objective lens, the aberration corrector specifically compensates aberrations introduced by components downstream of the deflector, while avoiding compensation of aberrations from components upstream, allowing for precise control of the beam's angle of incidence and focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an aberration corrector compensates all aberrations from all lenses, then imaging quality improves, but the ability to vary beam angle of incidence is lost
Solution Approach 1:
The aberration correction is segmented into two distinct zones: one for compensating aberrations from condenser lenses (upstream of deflector) and another for compensating aberrations from objective lens (downstream of deflector). This is achieved by placing the aberration corrector at a specific location and using separate control mechanisms for each lens group, allowing independent optimization of each zone's aberration compensation while preserving beam angle variability.
2Adaptability or versatility
If the beam is tilted at high angles for 3D imaging, then three-dimensional structure information is obtained, but aberrations increase and focus quality deteriorates
Solution Approach 1:
The aberration corrector is configured to preemptively compensate for aberrations that will be introduced by high-angle beam tilting during 3D imaging. By anticipating and correcting these aberrations before they significantly degrade the beam focus, the system maintains small focus diameters even when operating at high tilt angles necessary for three-dimensional specimen analysis.
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 compensation of aberrations, enabling clearer and more accurate three-dimensional imaging by maintaining the focus and reducing distortions caused by tilted angles, thus enhancing the reconstruction of specimen structures.
Implementation Method 1
an objective lens configured to focus the charged particle beam in an object plane
Implementation Method 2
a deflector disposed in a beam path of the charged particle beam between the charged particle beam source and the objective lens
Implementation Method 3
an aberration corrector configured to compensate aberrations introduced by components located in the beam path downstream of the deflector while avoiding compensation of aberrations introduced by components located in the beam path upstream of the deflector
Data Source
AI summary
A charged particle beam system includes a charged particle beam source to generate a charged particle beam; an objective lens to focus the charged particle beam in an object plane; a first condenser lens disposed in a beam path of the charged particle beam between the charged particle beam source and the objective lens; a deflector disposed in the beam path between the first condenser lens and the objective lens and configured to change an angle of incidence of the charged particle beam in an object plane; and an aberration corrector disposed in the beam path between the deflector and the objective lens and configured to compensate aberrations introduced by the objective lens. The aberration corrector is also configured to not compensate aberrations introduced by the first condenser lens.