Sample Stage Tilt Setting from Boundary and Vanishing Angles
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Solution Overview
Problem
Existing charged particle beam devices struggle to accurately set the tilt angle of a sample stage when the observation surface is larger than the field of view, leading to incomparable image areas and inability to decide the tilt angle.
Innovation Solution
A charged particle beam device with a sample stage that tilts along two intersecting axes, equipped with boundary and upper surface detection units to calculate tilt angles and an initial sample direction, allowing for appropriate tilt angle setting even when the observation surface exceeds the field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the observation surface is larger than the field of view, then the sample stage tilt angle cannot be accurately determined, but reducing the observation surface area limits the measurable sample regions
Solution Approach 1:
The patent transitions from 2D image area comparison to 3D geometric modeling by introducing boundary tilt angles and vanishing angles. By calculating the intersection of boundary lines from multiple tilt angle images and determining where they converge (vanish), the system accurately determines sample stage orientation even when the observation surface exceeds the field of view at any single tilt angle.
Solution Approach 2:
The patent introduces boundary lines between different sample surfaces (e.g., upper surface and cleavage surface) as intermediary elements. These boundary lines serve as reference features that can be tracked across multiple tilt angle images, enabling accurate geometric reconstruction and tilt angle determination without requiring the entire observation surface to be visible in each image.
2Measurement precision
If multiple tilt angle images are captured to determine sample orientation, then measurement accuracy improves, but image area comparability deteriorates when observation surface exceeds field of view
Solution Approach 1:
The patent changes the parameter used for comparison from absolute image area to boundary line geometry. By extracting boundary lines between sample surfaces at different tilt angles and calculating their intersection points and vanishing angles, the system achieves consistent orientation measurement that is independent of the varying observable area at each tilt angle.
Solution Approach 2:
The patent performs preliminary extraction and tracking of boundary lines across multiple tilt angle images before performing the final orientation calculation. By identifying and following these boundary features through the tilt angle series, the system establishes a consistent reference framework that enables accurate orientation determination regardless of area variations.
Data Source
AI summary
There are provided a charged particle beam device capable of appropriately setting a tilt angle of a sample stage even if an observation surface is larger than the field of view, and a sample observation method using the same. The charged particle beam device is a device for obtaining an observation image of a sample by irradiating the sample with a charged particle beam, and is characterized by including: a sample stage that tilts with respect to each of two tilt axes intersecting with each other and holds the sample as well; a boundary detection unit that detects a boundary between an upper surface and a cleavage surface of the sample from each observation image obtained while changing a tilt angle of the sample stage, and calculates a tilt of the boundary with respect to the scanning direction of a charged particle beam; an upper surface detection unit that detects the upper surface from the observation image for each tilt angle, and calculates an upper surface vanishing angle that is a tilt angle of the sample stage at which the upper surface vanishes from the observation image; and a calculation processing unit that calculates an initial sample direction, which is a direction of the cleavage surface when the tilt angle is zero, on the basis of the tilt of the boundary for each tilt angle and the upper surface vanishing angle.