Electron Shielding Timing for Sample Discharge Sensor Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Scanning non-conductive or partially conductive sample regions with an electron beam leads to surface charging, which degrades the quality of the image by reducing the signal-to-noise ratio and potentially damages sensors in the evaluation system.
Innovation Solution
A system is implemented with an electron shielding unit and a timing circuit that controls the electron beam and laser beam interactions to protect sensors by allowing electron emission during evaluation and shielding during discharging iterations, based on specific timing constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the region is scanned multiple times with an electron beam to improve the signal-to-noise ratio, then the image quality is improved, but the surface charging increases and degrades the frame quality
Solution Approach 1:
A timing circuit is introduced as an intermediary component that coordinates between the electron beam scanning operations and the laser beam discharging operations. The timing circuit generates control signals that synchronize the laser discharging with the electron beam scanning, allowing the laser to neutralize surface charge during idle periods without interfering with the image acquisition process
Solution Approach 2:
The laser beam is applied periodically during idle periods between electron beam scans or between multiple scans of the same region. This periodic discharging action removes accumulated surface charge before the next electron beam scan, preventing charge degradation of image quality while maintaining the benefits of multiple scans for improved signal-to-noise ratio
2Object-generated harmful factors
If a laser beam is used to discharge the surface of the region, then the surface charging is reduced, but electrons are emitted that may damage the sensor
Solution Approach 1:
The harmful electrons emitted during laser discharging are extracted from the system by blocking them with an electron beam shield. The shield is positioned to intercept these electrons during the discharging iteration, allowing the laser to effectively discharge the surface while preventing the emitted electrons from reaching and damaging the sensor
Solution Approach 2:
The timing circuit serves as an intermediary that coordinates the electron beam shield with the laser beam operation. It generates control signals that activate the electron beam shield precisely during the discharging iteration when the laser is active, creating a protective barrier that allows the laser to discharge the surface without exposing the sensor to harmful electrons
3Object-affected harmful factors
If the electron beam shield is activated during the discharging iteration, then the sensor is protected from electron damage, but the discharging process cannot proceed simultaneously with evaluation
Solution Approach 1:
The system alternates between evaluation iterations (electron beam scanning) and discharging iterations (laser beam with electron shield). The timing circuit schedules these iterations periodically, utilizing idle periods between scans for discharging operations. This periodic alternation allows both functions to occur without simultaneous conflict, maintaining sensor protection while minimizing impact on overall scanning 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 effectively reduces surface charging without damaging sensors, improving the signal-to-noise ratio and maintaining the quality of the scanning process.
Implementation Method 1
electrons emitted from a region of a sample when the region is illuminated with an electron beam
Implementation Method 2
electrons emitted from the region when the region is illuminated with a laser beam
Implementation Method 3
shield, under the control of the timing circuit, the sensor from electrons emitted from the region during a discharging iteration
Data Source
AI summary
A system for protecting a sensor, the system includes a controller and an electron shielding unit that is located upstream to the sensor and is configured to: (i) enable, under a control of the controller, electrons emitted from the region to reach the sensor during an evaluation iteration in which a region of the sample is illuminated with an electron beam, and (ii) shield, under the control of the controller, the sensor from electrons emitted from the region during a discharging iteration in which the region is illuminated with a laser beam, wherein a timing of the discharging iteration is based on one or more timing constraints associated with the evaluation iteration.