Multi-Beam Writing Apparatus Beam Position Correction
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Solution Overview
Problem
In multi-beam writing processes, systematic deviations in beam positions due to optical system characteristics can lead to decreased writing accuracy, especially when the number of beams is high, as it becomes difficult to provide independent deflection mechanisms for each beam, and existing irradiation amount modulation processing relies on pre-calculated coefficient data that may not account for changes during writing, such as focal point corrections and beam axis deviations.
Innovation Solution
A method that acquires position deviation data for various parameter values, calculates reference coefficient data, and uses these to modulate irradiation amounts for each beam, allowing for real-time correction of beam positions and maintaining high writing accuracy even when the position deviation map changes during writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beams is significantly large in the multi-beam writing apparatus, then the throughput is improved, but it becomes difficult to provide an independent deflection mechanism for each beam to correct position deviations
Solution Approach 1:
The patent combines the deflection control of multiple beams into a single shared deflection mechanism rather than providing independent deflection mechanisms for each beam. The blanking aperture array with pairs of electrodes collectively controls all beams, reducing device complexity while maintaining the ability to correct position deviations through coordinated control of the shared mechanism.
Solution Approach 2:
The shared deflection mechanism serves multiple functions: it deflects all beams collectively for positioning and also enables individual beam blanking through the blanking aperture array. This multi-functional approach allows a single mechanism to handle both beam steering and beam selection, reducing the overall number of components needed.
2Loss of time
If pre-calculated coefficient data is used for irradiation amount modulation, then the writing process can start promptly, but the position deviation map may change during writing due to focal point correction and beam axis deviation
Solution Approach 1:
The patent performs preliminary calculation of coefficient data before the writing process to enable prompt start. The position deviation map is measured and coefficient data is calculated in advance, allowing the writing process to begin without delay while having correction parameters ready for application during writing.
Solution Approach 2:
The patent implements dynamic recalculation of coefficient data during the writing process. When the position deviation map changes due to focal point correction or beam axis deviation, the system recalculates the coefficient data to reflect current conditions, ensuring that the irradiation amount modulation remains accurate throughout the writing process.
3Device complexity
If coefficient data is calculated in advance before writing processing, then computational complexity is reduced, but the position deviation map changes during writing processing
Solution Approach 1:
The patent calculates coefficient data in advance before writing processing to reduce computational complexity during the writing process. This preliminary calculation prepares the correction parameters ahead of time, simplifying the real-time operations during writing while maintaining the ability to recalculate if conditions change.
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors changes in the position deviation map during writing processing. When changes exceed certain thresholds (such as focal point correction or beam axis deviation), the system triggers recalculation of coefficient data to maintain writing accuracy, creating a closed-loop control system.
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 reduces computational complexity and enables prompt start of writing processes while ensuring high accuracy by recalculating correction coefficient data as needed, thereby mitigating the effects of beam position deviations on the dose distribution.
Implementation Method 1
an electron beam emitted from one electron gun is caused to pass through a shaping aperture array having a plurality of openings to form multi-beam (a plurality of electron beams)
Implementation Method 2
The blanking aperture array has pairs of electrodes that individually deflect the beams, and an opening for allowing a beam to pass therethrough is formed between each pair of electrodes. Blanking deflection is performed on an electron beam passing through the opening by fixing one of the pair of electrodes (a blanker) to a ground potential and switching the other electrode between the ground potential and a potential other than the ground potential.
Data Source
AI summary
In one embodiment, a multi-beam writing method includes acquiring a plurality of pieces of position deviation data corresponding to a plurality of parameter values of a parameter that change position deviation amount of each beam of multi-beam irradiated on a substrate, calculating a plurality of pieces of reference coefficient data corresponding to each of the plurality of pieces of position deviation data, calculating coefficient data corresponding to a parameter value at an irradiation position of the multi-beam on the substrate using the plurality of pieces of reference coefficient data corresponding to the plurality of parameter values, modulating an irradiation amount of each beam of the multi-beam for each shot using the coefficient data, and writing a pattern by irradiating the substrate with each beam of at least a part of the multi-beam having the modulated irradiation amounts.