Electron Beam Dynamic Focus Adjustment via Multi-Electrode Compensation
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Solution Overview
Problem
In electron beam irradiation apparatuses, the increasing strength of the magnetic field generated by the objective lens can lead to a negative space potential being formed, which affects the trajectory of the electron beam, causing precision issues during dynamic focus adjustment and pattern writing.
Innovation Solution
An electron beam dynamic focus adjustment method using an annular multi-stage electrode system, where a positive potential is variably applied to the second-stage electrode, and the potentials applied to the first-stage and third-stage electrodes are fixed, with the second potential being higher than the first, to prevent the formation of a negative space potential by removing low-energy component electrons to the side of the first-stage electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic field strength of the objective lens is increased to improve focusing capability, then the focusing precision is improved, but a negative space potential is formed that affects the electron beam trajectory
Solution Approach 1:
An electrostatic lens is introduced as an intermediary device between the deflector and the objective lens. This electrostatic lens generates an electric field that counteracts the negative space potential formed by the strong magnetic field of the objective lens, thereby eliminating the harmful effect on electron beam trajectory while maintaining high focusing precision
Solution Approach 2:
The patent combines magnetic field (from objective lens) and electric field (from electrostatic lens) to achieve a composite field system. The electric field component compensates for the harmful negative space potential while the magnetic field provides strong focusing, creating a synergistic effect that resolves the contradiction
2Manufacturing precision
If dynamic focus adjustment is performed on uneven surfaces to improve writing precision, then the manufacturing precision is improved, but the electron beam trajectory is affected by the negative space potential
Solution Approach 1:
The electrostatic lens acts as a mediator that enables dynamic focus adjustment on uneven surfaces by compensating for trajectory deviations caused by the negative space potential, allowing precise writing without beam trajectory interference
3Device complexity
If a simple single-stage electrode is used for focus adjustment, then the device complexity is reduced, but the ability to control and eliminate negative space potential is insufficient
Solution Approach 1:
The electrostatic lens is divided into three separate electrode stages (first-stage, second-stage, and third-stage electrodes). This segmentation allows independent control of electric field strength at different positions, enabling precise compensation of the negative space potential while maintaining a relatively simple overall structure
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 approach allows for precise dynamic focus adjustment on uneven surfaces without affecting the electron beam trajectory, enhancing the precision of electron beam writing and irradiation processes.
Implementation Method 1
a first electrode being annular, arranged along an optical axis of the electron beam, at a position downstream from the deflector, and in a magnetic field of the objective lens
Implementation Method 2
an annular three-stage electrode is used, wherein a ground potential is applied to the upper and lower electrodes and a positive potential, for example, to be applied to the second-stage electrode is variably adjusted, thereby performing a dynamic focus adjustment
Implementation Method 3
an objective lens configured to focus the electron beam to form an image on the surface of the target object
Implementation Method 4
a deflector configured to deflect the electron beam to a desired position on a surface of a target object
Data Source
AI summary
An electron beam irradiation apparatus includes a first electrode being annular, arranged along the optical axis of the electron beam, at the downstream from the deflector, and in the magnetic field of the objective lens, to which a first potential being positive is variably applied, a second electrode being annular, arranged in the magnetic field of the objective lens and between the deflector and the first electrode, to which a second potential being positive and higher than the first potential is applied, and a third electrode being annular, arranged in the magnetic field of the objective lens and to be opposite to the second electrode with respect to the first electrode, to which a third potential lower than the first potential is applied.