Beam Blanking Duty Ratio Control for Tilted Sample Tomography
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Solution Overview
Problem
Conventional charged particle beam systems require excessively long data acquisition times when controlling electron beam dose for tomography, leading to sample drift and image quality deterioration due to prolonged exposure and beam irradiation damage.
Innovation Solution
A charged particle beam system with a beam blanker, sample stage, and controllers to adjust the duty ratio of a pulsed beam based on the sample's tilt angle, ensuring consistent electron beam dose and reducing acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the exposure time is lengthened with increasing tilt angle to maintain consistent electron beam dose, then the electron beam dose can be controlled uniformly, but the data acquisition time becomes excessively long
Solution Approach 1:
The patent applies periodic action by using a pulsed electron beam instead of continuous illumination. The beam is turned on and off in periodic cycles, allowing the system to accumulate sufficient dose over multiple pulses without requiring excessively long continuous exposure times at each tilt angle. This resolves the contradiction by maintaining dose control while significantly reducing total acquisition time.
Solution Approach 2:
The patent implements dynamics by making the duty ratio of the pulsed beam adjustable based on the tilt angle. As the tilt angle changes, the system dynamically modifies the beam's on/off cycle ratio to maintain consistent dose delivery. This dynamic adjustment allows the system to adapt to varying sample thicknesses at different angles without requiring uniformly long exposure times.
2Manufacturing precision
If the exposure time is extended to control electron beam dose, then dose uniformity is achieved, but sample drift occurs and image quality deteriorates
Solution Approach 1:
By using periodic pulsed beam illumination rather than continuous exposure, the system achieves the necessary cumulative dose while minimizing the total time the sample is exposed to the beam. This reduces sample drift during acquisition and maintains image quality, while still achieving dose uniformity through the controlled pulse cycles.
3Manufacturing precision
If the data acquisition time is prolonged to control electron beam dose, then dose consistency is maintained, but beam irradiation damage to the sample increases
Solution Approach 1:
The periodic pulsed beam delivery system maintains consistent cumulative dose by controlling the number and duration of pulses, while the intermittent off-periods allow the sample to recover between exposures. This significantly reduces total beam irradiation damage compared to continuous exposure, while maintaining dose consistency across different tilt angles through dynamic duty ratio adjustment.
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 prevents prolonged data acquisition times, minimizes sample drift, and reduces beam-induced damage by maintaining a consistent electron beam dose across varying tilt angles, enhancing image quality.
Implementation Method 1
the beam blanker may be electrostatic deflecting plates
Data Source
Figure 1~2
Figure 3
AI summary
There is provided a charged particle beam system capable of preventing the data acquisition time from increasing. A control method for the system is also provided. The charged particle beam system (1) includes: a beam blanker (12) for blanking a charged particle beam; a sample stage (15) on which a sample (S) is tiltably held and thus can assume a tilt angle; a blanking controller (102) for controlling the blanking of the charged particle beam and causing a pulsed beam having a duty ratio to be directed at the sample (S); and a tilt controller (104) for controlling the tilt angle (θ) of the sample (S). The blanking controller (102) sets the duty ratio (DR) of the pulsed beam based on the tilt angle (θ) of the sample (S).