Particle Beam Focusing Using Neighboring Defocus Measurements
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Solution Overview
Problem
Existing charged particle beam systems face challenges in achieving uniform and high-quality images across regions of a sample due to variations in sample height and environmental factors, which require time-consuming focus adjustments and auxiliary imaging.
Innovation Solution
The method involves determining focus adjustments for a region of a sample based on defocus measurements from neighboring regions, allowing for adaptive focusing of particle beams to achieve targeted defocus without the need for auxiliary imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional focus adjustment methods are used for each region, then image quality can be maintained, but processing time increases and throughput decreases
Solution Approach 1:
The patent performs focus measurements on neighboring regions before imaging the target region, and uses these preliminary measurements to predict and set the optimal focus for the target region. This preliminary action eliminates the need for time-consuming focus adjustments during actual imaging, thereby maintaining image quality while increasing throughput
Solution Approach 2:
The patent copies focus information from neighboring regions to the target region by measuring defocus in adjacent areas and applying these measurements to predict the optimal focus setting for the target region. This copying approach avoids direct measurement and adjustment at each location, reducing processing time while maintaining quality
2Measurement precision
If auxiliary imaging is performed to determine focus settings, then accurate focus can be achieved, but sample damage increases and processing time decreases
Solution Approach 1:
The patent copies focus information from neighboring regions that have already been imaged to the target region. By reusing defocus measurements from adjacent areas, the system determines accurate focus settings without performing additional auxiliary imaging on the target region, thereby reducing cumulative sample damage
Solution Approach 2:
The patent uses defocus measurements from neighboring regions as feedback to determine the optimal focus setting for the target region. This feedback mechanism allows accurate focus determination without requiring auxiliary imaging of the target region itself, reducing sample exposure to damaging electron beams
3Manufacturing precision
If focus adjustments are made for each region, then uniform image quality can be achieved, but processing time increases
Solution Approach 1:
The patent applies local quality by determining focus settings specific to each target region based on its unique characteristics and the defocus measurements from its neighboring regions. This localized approach ensures uniform image quality across different regions while avoiding the need for time-consuming focus adjustments at every location
Solution Approach 2:
The patent performs focus measurements on neighboring regions in advance and uses these preliminary results to predict optimal focus settings for target regions. This preliminary action eliminates the need for time-consuming focus adjustments during actual imaging, achieving uniform quality across regions while reducing processing time
Data Source
AI summary
Various approaches are provided for automatically focusing particle beams for SPA. In one example, a method includes determining a focus adjustment for a region of a sample to achieve a targeted defocus based on at least one defocus measurement from at least one neighboring region of the sample, and causing an acquisition of an image of the sample at the region with the focus adjustment. In this way, a targeted defocus may be achieved across regions of a sample with reduced auxiliary imaging, thereby providing increased and uniform image quality while reducing the time and thus increasing the throughput of processing.