Suppressor Electrode Tapering for Electron Beam Alignment Stability
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Solution Overview
Problem
The alignment shift between the central axes of the tip and the suppressor electrode in electron sources leads to off-axis aberration and machine differences in electron microscopes, affecting resolution and increasing manufacturing costs and lead times.
Innovation Solution
The suppressor electrode is designed with a receding portion in the form of a tapered surface near the central axis, which mitigates the bending of the electron beam even when axial shifts occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the tip and suppressor electrode are mechanically aligned and assembled to be coaxial, then the electron beam alignment is improved, but the manufacturing complexity and lead time increase due to high precision requirements
Solution Approach 1:
The suppressor electrode is designed with an asymmetric tapered receding portion that intentionally creates a specific geometric asymmetry to counterbalance the random alignment errors. This asymmetric structure generates a compensating electric field that offsets the beam bending caused by misalignment, thereby resolving the contradiction between achieving high alignment precision and reducing assembly complexity.
Solution Approach 2:
The invention changes the geometric parameters of the suppressor electrode by adding a tapered receding portion with specific dimensions (taper angle α between 15-45 degrees, receding length L1 of 0.5-2mm). This parameter modification allows the electrode to function effectively even when alignment precision varies, reducing the stringency of assembly requirements while maintaining beam quality.
2Measurement precision
If the axial shift between tip and suppressor electrode is reduced, then the resolution is improved, but the manufacturing cost and lead time increase
Solution Approach 1:
The tapered receding portion is designed in advance to provide a cushioning effect against alignment errors. This pre-designed geometric feature creates an electric field distribution that compensates for potential beam bending before it occurs, allowing for faster, less precise assembly while maintaining resolution performance.
Solution Approach 2:
The invention accepts that individual electron sources may have varying alignment characteristics and designs the suppressor electrode to be a simple, easily manufacturable component that can be produced with standard tolerances. This approach prioritizes manufacturing efficiency over individual component precision, reducing lead time while maintaining overall system performance through the compensating geometry.
3Reliability
If the axial shift between tip and suppressor electrode occurs, then the machine difference increases, but reducing the shift amount increases manufacturing complexity
Solution Approach 1:
The asymmetric tapered receding portion creates a universal compensating mechanism that works across different electron source configurations. This single geometric modification provides robustness against alignment variations, ensuring consistent performance across multiple devices without requiring complex individual adjustments for each unit.
Solution Approach 2:
The tapered receding portion serves multiple functions: it maintains the suppressor electrode's primary function of suppressing thermal electrons while simultaneously compensating for alignment errors. This multi-functionality reduces the need for additional complex components, maintaining reliability across devices without proportionally increasing structural complexity.
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 design reduces machine differences by maintaining electron beam alignment, enhancing resolution and preventing manufacturing failures in electron microscopes.
Implementation Method 1
The suppressor electrode has a function of suppressing unnecessary thermal electrons emitted from portions other than the distal end portion of the tip by applying a negative potential to the tip distal end
Implementation Method 2
the electrons are emitted from a tip distal end by heating the tip and applying an electric field by the extraction electrode
Data Source
AI summary
In an electron source including a suppressor electrode having an opening at one end portion thereof in a direction along a central axis and an electron emission material having a distal end protruding from the opening, the suppressor electrode further includes a receding portion receding to a position farther from the distal end of the electron emission material than the opening in the direction along the central axis at a position in an outer peripheral direction than the opening, and at least a part of the receding portion is disposed within a diameter of 2810 μm from a center of the opening. Accordingly, an electron source, an electron gun, and a charged particle beam device such as an electron microscope using the same, in which a machine difference in a device performance due to an axial shift between the electron emission material and the suppressor electrode is reduced, are implemented.