Multibeam Scanning Electron Beam Distortion Control
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Solution Overview
Problem
Multibeam scanning electron microscopes face issues with distortions and erroneous detection of secondary beams due to the close proximity of adjacent scan regions, leading to suboptimal image quality and accuracy in semiconductor inspections.
Innovation Solution
The multibeam scanning apparatus separates each scan region into multiple orthogonal sections, allowing primary beams to be scanned at different times to avoid overlapping and reduce the influence of electrical charges, thereby minimizing distortions and improving image quality by controlling the irradiation positions of electron beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams scan adjacent scan regions simultaneously, then productivity is improved by acquiring wide area images quickly, but distortions and erroneous detections occur due to close proximity of scan regions
Solution Approach 1:
The patent divides the observation area into multiple scan regions that are scanned by different electron beams simultaneously. Each scan region is further divided into sub-regions with specific scanning patterns, allowing parallel processing while maintaining detection accuracy through spatial separation and controlled scanning sequences.
Solution Approach 2:
The patent implements periodic scanning patterns where electron beams scan adjacent scan regions in an alternating or staggered sequence rather than simultaneously. This periodic action reduces charge accumulation effects and minimizes distortions while maintaining high productivity through efficient time-multiplexed scanning.
2Area of stationary object
If scan regions are positioned closely to maximize coverage area, then area of observation is improved, but electrical charge interference increases causing image quality degradation
Solution Approach 1:
The patent applies different scanning patterns and control parameters to different local regions. Adjacent scan regions use staggered or alternating scanning sequences, while central regions may use different patterns compared to edge regions. This local quality approach optimizes each region's scanning behavior to minimize charge interference while maintaining overall coverage.
Solution Approach 2:
The patent dynamically adjusts scanning parameters such as beam current, scanning speed, and region activation sequences based on real-time conditions. The control unit modifies scanning patterns to reduce charge accumulation in densely scanned areas while maintaining productivity, making the system adaptive to prevent charge interference effects.
3Productivity
If multiple beams are scanned at the same time to increase efficiency, then productivity is improved, but distortions occur due to overlapping scan lines
Solution Approach 1:
The patent segments the scanning process into distinct temporal phases where different electron beams scan different sub-regions at different times. By dividing the observation area into multiple non-overlapping scan regions and assigning them to different beams with staggered timing, the system maintains high productivity while eliminating scan line distortions caused by simultaneous scanning.
Solution Approach 2:
The control unit pre-plans and coordinates the scanning sequences of multiple electron beams to ensure that adjacent scan regions are scanned in an optimal sequence. This preliminary coordination prevents overlapping scan lines and distortions by establishing proper timing and spatial relationships before scanning begins, while still enabling parallel processing for high 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 distortions and erroneous detections, enhancing the quality and accuracy of observation images by ensuring that adjacent scan regions are scanned at different times, thus improving the overall inspection process.
Implementation Method 1
emit a plurality of electron beams to a plurality of scan regions set in a matrix on an object and obtain an observation image by detecting secondary beams generated from the scan regions
Data Source
AI summary
A multibeam scanning apparatus of an embodiment is a multibeam scanning apparatus configured to emit a plurality of electron beams to a plurality of scan regions set in a matrix on an object and obtain an observation image by detecting secondary beams, the apparatus including a control circuit. Each of the scan regions includes a plurality of separated scan regions obtained by separating the each of the scan regions in a direction orthogonal to a scanning direction of the electron beams. The control circuit controls the irradiation positions of the electron beams, in two of the scan regions adjacent to each other in the scanning direction of the electron beams, such that the separated scan regions to be scanned at a same time are displaced from each other by a predetermined distance in the direction orthogonal to the scanning direction of the electron beams.