Secondary Electron Beamlet Alignment for Multi-Beam Detector Imaging
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Solution Overview
Problem
Existing multi-beam charged particle imaging systems face challenges in maintaining precise alignment of secondary electron beamlets with detection elements, leading to reduced signal strength and increased cross-talk, requiring frequent recalibration of monitoring systems.
Innovation Solution
The system employs a mechanism to monitor and adjust the raster configuration of secondary electron beamlets on a detector with high precision, allowing for real-time adjustments to maintain optimal alignment without frequent recalibration, thereby enhancing signal strength and reducing cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the raster configuration of secondary electron beamlets is monitored and adjusted with high precision, then alignment accuracy with detection elements is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the actual positions of secondary electron beamlets are continuously monitored and compared with the ideal raster configuration. Deviations are detected and used to generate correction signals that adjust the beamlet positions, creating a closed-loop control system that maintains high alignment accuracy without requiring overly complex mechanical structures
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with electronic control methods. Instead of using precision mechanical stages to physically reposition detection elements, the system uses electronic signals to control electrostatic or magnetic deflectors that adjust beamlet positions, thereby reducing mechanical complexity while maintaining alignment precision
2Reliability
If real-time adjustments are made to maintain optimal alignment, then signal strength is improved, but processing time increases
Solution Approach 1:
The patent implements continuous monitoring and adjustment of beamlet positions rather than periodic recalibration. The feedback system operates continuously during imaging, constantly detecting position deviations and applying corrections in real-time, which maintains optimal signal strength without requiring time-consuming stop-and-adjust cycles
Solution Approach 2:
The patent performs preliminary alignment adjustments during system initialization and before imaging begins. This preliminary configuration establishes optimal beamlet-to-detection-element alignment, reducing the need for frequent adjustments during operation and minimizing processing time interruptions
3Measurement precision
If frequent recalibration of monitoring systems is performed, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent implements a self-calibrating system where the monitoring system automatically detects and corrects its own drift without requiring external intervention. The system uses built-in reference signals and internal feedback loops to maintain measurement precision continuously, eliminating the need for frequent manual recalibration that would reduce productivity
Solution Approach 2:
The patent introduces an intermediary reference system that mediates between the beamlet positions and detection elements. This reference system provides stable reference signals that enable continuous precision measurement without requiring direct repeated calibration of the entire monitoring system, thereby maintaining measurement accuracy while preserving productivity
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 approach improves the throughput and accuracy of multi-beam charged particle imaging systems by maintaining maximum signal strength and minimizing noise and cross-talk, ensuring high imaging precision and reliability.
Implementation Method 1
a secondary electron optical imaging system for focusing a plurality of secondary beamlets and for forming a plurality of focus points of the secondary beamlets in an image plane
Implementation Method 2
the detector comprises a plurality of sets of detection elements with one set of detection elements for each secondary electron beamlet, wherein each set of detection elements is configured to record an intensity signal of the assigned secondary electron beamlet
Data Source
AI summary
A multi-beam charged particle beam system and a method of operating a multi-beam charged particle beam system with higher precision are configured for a determination of an assignment of secondary electron focus spot to a plurality of sets of detection elements. The system and method are further configured to adjust the assignment and for a calibration of a monitoring method and system for monitoring the assignment. The system and method are applicable for an inspection of samples, for example for wafer or mask inspection.