Axisymmetric Multipole Lens Structure for Chromatic Aberration
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Solution Overview
Problem
Existing aberration correctors in charged particle beam apparatuses require high mechanical positional accuracy for arranging current lines, and additional electric fields are necessary to correct chromatic aberration, complicating the manufacturing process.
Innovation Solution
A charged particle beam apparatus with a multi-pole lens that includes a magnetic core with axisymmetrically arranged grooves for current lines and electrodes, allowing for precise control of magnetic and electric fields without significant positional deviations, using a conductive shield to maintain reference potential and separate magnetic and electric field regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multi-pole fields are generated using current lines without a magnetic core, then the aberration corrector can be achieved with a relatively inexpensive multi-pole correction system, but high mechanical positional accuracy is required for arranging the current lines
Solution Approach 1:
A magnetic core is introduced as an intermediary component between the current lines and the surrounding structure. The magnetic core provides a physical reference framework with pre-formed grooves that guide current line placement, thereby reducing the positional accuracy requirements for current line arrangement while maintaining the cost-effectiveness of the multi-pole correction system
Solution Approach 2:
The magnetic core is segmented with multiple grooves formed at axisymmetric positions around its circumference. These grooves divide and organize the current lines into distinct, predetermined locations, making the assembly process more tolerant of manufacturing variations while ensuring proper spatial distribution of the multi-pole fields
2Measurement precision
If electric field is excited in addition to magnetic field to correct chromatic aberration, then the resolution of the electron microscope can be increased, but it is necessary to arrange an electrode for exciting the electric field in the multi-pole lens, complicating the manufacturing process
Solution Approach 1:
The electrode structure is merged with the existing magnetic core and groove framework. The electrodes are arranged in correspondence with the grooves, allowing the same structural reference system to serve both magnetic field generation (via current lines in grooves) and electric field generation (via electrodes in corresponding positions), thereby reducing overall structural complexity
Solution Approach 2:
The magnetic core with grooves serves multiple functions: it provides structural support, guides current line placement for magnetic field generation, and serves as a reference framework for electrode positioning for electric field generation. This multi-functionality reduces the need for separate positioning systems and simplifies the overall manufacturing process
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 configuration enables effective correction of chromatic aberration and simplifies the manufacturing process by reducing the need for high positional accuracy of current lines and electric field arrangement, facilitating control of aberrations.
Implementation Method 1
a plurality of current lines, main line portions of the plurality of current lines are arranged axisymmetrically with respect to a central axis of the magnetic core along an inner wall of the magnetic core
Implementation Method 2
a plurality of wire-shaped electrodes, portions of the plurality of electrodes parallel to the central axis of the magnetic core are arranged axisymmetrically with respect to the central axis of the magnetic core
Implementation Method 3
a conductive shield set to a reference potential, which is provided between the electrode fixing portion and a central axis of the magnetic core
Data Source
AI summary
A charged particle beam apparatus including a winding aberration corrector capable of correcting a chromatic aberration is provided. A multi-pole lens includes a magnetic core 150, a plurality of current lines 101 to 112, a plurality of wire-shaped electrodes 301 to 312, insulating electrode fixing portions 313 to 342 for fixing the plurality of electrodes to a structure in a vacuum container, and conductive shields 320, 321 set to a reference potential, which are provided between the electrode fixing portion and a central axis of the magnetic core, main line portions of the plurality of current lines are arranged axisymmetrically with respect to the central axis of the magnetic core along an inner wall of the magnetic core, and portions of the plurality of electrodes parallel to the central axis of the magnetic core are arranged axisymmetrically with respect to the central axis of the magnetic core.