Sample Positioning in Charged Particle Beam Apparatus
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Solution Overview
Problem
Charged particle beam apparatuses face difficulties in quickly and accurately positioning small, randomly distributed target observation areas within a narrow field of view, especially when using multiple beams, due to the limited depth of focus and large depth of field, leading to inefficient sample positioning.
Innovation Solution
A method and apparatus that utilize a display unit to align the sample stage with the charged particle beam's optical axis, employing on-axis point tracer planes and sub-marks to guide the movement of the sample stage in both perpendicular and axial directions, ensuring precise positioning within the beam's field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a charged particle beam is used to observe target observation areas, then high magnification and detailed observation are achieved, but the field of view becomes very narrow making it difficult to locate randomly distributed targets
Solution Approach 1:
The patent introduces a depth dimension by creating multiple on-axis point tracer planes at different depth positions along the optical axis. This allows the system to track target positions not only in the lateral plane but also in the depth direction, effectively adding a third dimension to the positioning process and solving the problem of locating targets in a narrow field of view
2Loss of time
If the field of view is increased to locate targets easily, then target acquisition becomes faster, but the magnification and observation detail are reduced
Solution Approach 1:
The patent performs preliminary positioning actions by first locating the target in the lateral plane using the on-axis point tracer plane, then systematically adjusting the depth position. This preliminary action in the lateral plane provides a starting point that reduces the time needed for subsequent depth positioning, while maintaining the ability to achieve high magnification observation
3Adaptability or versatility
If multiple charged particle beam columns are used to increase functionality, then more observation angles and capabilities are achieved, but the positioning complexity increases significantly
Solution Approach 1:
The patent creates on-axis point tracer planes that serve multiple functions: they indicate the optical axis position, provide depth reference planes for positioning, and work across multiple charged particle beam columns. This universal positioning method can be applied to any number of beam columns, reducing the complexity increase that would otherwise result from adding multiple observation systems
4Length of stationary object
If the depth of focus is increased to accommodate larger depth of field, then more sample depth is observable, but the positioning precision in the depth direction becomes less accurate
Solution Approach 1:
The patent segments the depth space into multiple discrete on-axis point tracer planes at different depth positions. Each plane serves as a precise reference level, allowing the system to accurately identify which depth plane contains the target. This segmentation approach maintains high depth positioning accuracy even when the overall depth of focus is increased to accommodate larger sample depth
Data Source
AI summary
A sample positioning method that can easily and quickly position a target observation area of a sample, which is disposed on a sample stage in a sample chamber of a charged particle beam apparatus, into a field of view of a first charged particle beam. The method includes displaying an image including the sample on a display screen; designating an attention point on the basis of the image on the display screen while maintaining the relative position of the attention point with respect to the sample stage; aligning the position of the sample stage in the direction of an optical axis so that the attention point is positioned in an on-axis point tracer plane perpendicular to the optical axis through an on-axis target point on the optical axis; moving the attention point to the on-axis target point by performing detection of deviation of the attention point from the on-axis target point and movement in the on-axis point tracer plane; and moving the attention point into a depth of focus of a charged particle beam optics.