Beam Separator Dispersion Compensation With Electrostatic-Magnetic Deflectors
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Solution Overview
Problem
Beam separators in single-beam and multi-beam charged particle beam apparatuses cause dispersion and astigmatism aberrations, leading to reduced resolution and detection efficiency, and require complex adjustments to maintain deflection angles, especially when primary beam energy changes.
Innovation Solution
Implement a dispersion device comprising an electrostatic deflector and a magnetic deflector to induce a beam dispersion that cancels the dispersion caused by the beam separator, maintaining a constant deflection angle and compensating for changes in primary beam energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a beam separator is used to separate the secondary beam from the primary beam, then the detector can be placed off-axis improving detection efficiency, but the beam separator generates dispersion that deforms the probe spot and deteriorates image resolution
Solution Approach 1:
A dispersion compensation device is introduced upstream of the beam separator to generate opposite dispersion that cancels the dispersion generated by the beam separator. This preliminary anti-action prevents the probe spot deformation and resolution deterioration before they occur, allowing the beam separator to function effectively for beam separation without compromising image quality
2Stability of the object's composition
If the beam separator is adjusted to maintain constant deflection angle when primary beam energy changes, then beam alignment is maintained, but the adjustment causes uncontrolled change in secondary beam deflection angle reducing detection efficiency
Solution Approach 1:
The deflection control is segmented into two independent parts: the beam separator controls the deflection angle for beam separation, while the dispersion compensation device controls the dispersion magnitude. This segmentation allows independent optimization - the beam separator can be adjusted for constant deflection angle while the dispersion compensation device maintains constant dispersion, preventing the coupled adjustment problem that reduced detection efficiency
3Reliability
If a beam separator with magnetic deflector is used to separate beams, then beam separation is achieved, but astigmatism aberration is added to the primary and secondary beams
Solution Approach 1:
A dispersion compensation device serves as an intermediary element upstream of the beam separator. This intermediary generates opposite dispersion that cancels the beam separator's dispersion, thereby compensating for the astigmatism aberration introduced by the magnetic deflector while preserving the beam separator's separation capability
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
The solution improves resolution and detection efficiency by canceling dispersion and astigmatism aberrations, simplifying the apparatus alignment and maintaining consistent deflection angles, thereby enhancing image quality in charged particle beam inspection systems.
Implementation Method 1
The electrostatic deflector exerts a first force on the beam
Implementation Method 2
the magnetic deflector exerts a second force on the beam
Data Source
AI summary
Systems and methods are provided for compensating dispersion of a beam separator in a single-beam or multi-beam apparatus. Embodiments of the present disclosure provide a dispersion device comprising an electrostatic deflector and a magnetic deflector configured to induce a beam dispersion set to cancel the dispersion generated by the beam separator. The combination of the electrostatic deflector and the magnetic deflector can be used to keep the deflection angle due to the dispersion device unchanged when the induced beam dispersion is changed to compensate for a change in the dispersion generated by the beam separator. In some embodiments, the deflection angle due to the dispersion device can be controlled to be zero and there is no change in primary beam axis due to the dispersion device.