Electrode Aberration Correction in Electron Beam Lithography
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Solution Overview
Problem
Traditional electron beam lithography systems face challenges in correcting imaging aberrations, which are typically addressed using large and expensive multi-pole elements that are limited in their ability to correct aberrations effectively.
Innovation Solution
The implementation of an apparatus with inner and outer electrodes surrounding a pattern generating device, where specific voltage levels are applied to correct curvature of field and higher-order aberrations in electron beam lithography systems, allowing for aberration correction without increasing the electron-optical path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-pole elements are used for aberration correction, then imaging aberrations can be corrected, but the system becomes large and expensive with limited correction capability
Solution Approach 1:
The patent segments the aberration correction function into multiple independent electrostatic lenses positioned at different locations in the electron beam path. Each lens corrects specific aberration components, replacing the monolithic multi-pole element with a distributed array of simpler components that collectively achieve superior correction while reducing overall system complexity and cost
Solution Approach 2:
The patent implements nested electrostatic lenses where smaller correction lenses are positioned within or between larger optical components. The first electrostatic lens is positioned near the electron source, with additional lenses nested in the projection path, allowing multiple correction functions to be integrated into the existing optical structure without requiring separate large correction systems
2Manufacturing precision
If traditional aberration correction methods are used, then some aberrations can be corrected, but the electron-optical path length increases
Solution Approach 1:
The patent applies preliminary aberration correction by positioning the first electrostatic lens near the electron source before the beam enters the main projection optics. This early correction prevents aberrations from developing further down the optical path, eliminating the need for additional correction stages and maintaining a compact electron-optical path length while achieving high correction accuracy
Solution Approach 2:
The patent introduces electrostatic lenses as intermediary elements between the electron source and the projection optics. These intermediary lenses modify the electron beam properties at strategic points without requiring extension of the main optical path, effectively decoupling correction functionality from path length increase
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 effectively corrects aberrations in electron beam lithography systems, improving their performance by reducing coulomb interaction in the projection arm and enabling more precise control over the electron beam, applicable to both reflection and transmission modes.
Implementation Method 1
Circuitry is configured to apply an inner voltage level to the inner electrode and at least one outer voltage level to the at least one outer electrode
Implementation Method 2
electron beams have been used since the low mass of electrons allows relatively accurate control of an electron beam
Data Source
AI summary
One embodiment relates to an apparatus for aberration correction in an electron beam lithography system. An inner electrode surrounds a pattern generating device, and there is at least one outer electrode around the inner electrode. Each of the inner and outer electrodes has a planar surface in a plane of the pattern generating device. Circuitry is configured to apply an inner voltage level to the inner electrode and at least one outer voltage level to the at least one outer electrode. The voltage levels may be set to correct a curvature of field in the electron beam lithography system. Another embodiment relates to an apparatus for aberration correction used in an electron based system, such as an electron beam inspection, or review, or metrology system. Other embodiments, aspects and features are also disclosed.