Multiple Charged Particle Beam Dose Correction for Writing Accuracy
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Solution Overview
Problem
In multiple beam writing processes, the non-uniform current densities of charged particle beams lead to current density distribution, resulting in inaccurate dose delivery and reduced throughput due to the need for extended beam irradiation times to correct singular current densities, which exacerbates quantization errors.
Innovation Solution
A method and apparatus that sets multiple weighting coefficients for each beam based on their arrangement positions, correcting the dose of each beam using these coefficients to ensure accurate dose delivery and reduce quantization errors while maintaining throughput by varying beam irradiation times across passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correction is performed for each shot using individual beam irradiation times to account for current density distribution, then writing accuracy is improved, but the shot cycle must match the maximum beam irradiation time, causing throughput to deteriorate
Solution Approach 1:
The patent segments the correction approach by dividing beams into groups based on their current density characteristics and arrangement positions. Instead of correcting each beam individually with unique irradiation times, beams with similar characteristics are grouped and corrected together, allowing the shot cycle to be determined by the maximum time among groups rather than individual beams, thus improving throughput while maintaining accuracy.
Solution Approach 2:
The patent changes the correction parameter from individual beam irradiation times to group-based correction coefficients. By calculating correction coefficients based on grouped current density averages rather than individual beam values, the system reduces the number of different irradiation time requirements, enabling more efficient shot cycle synchronization and improved throughput.
2Loss of time
If current densities of beams are averaged and a single correction coefficient is used for multiple beams, then singular beam irradiation times are suppressed, but quantization errors are stacked in the same manner, causing error in actual dose
Solution Approach 1:
The patent applies local quality by assigning different correction coefficients to different groups of beams based on their specific arrangement positions and current density characteristics. Instead of using a uniform correction coefficient for all beams, each group receives a tailored correction coefficient that accounts for its local current density profile, preventing quantization errors from stacking while maintaining consistent irradiation times across groups.
3Manufacturing precision
If beam irradiation time is extended to correct singular current densities, then dose accuracy is improved, but throughput is reduced due to longer writing time
Solution Approach 1:
The patent performs preliminary action by pre-calculating correction coefficients for groups of beams based on their current density characteristics before the actual writing process. This allows the system to determine optimal shot cycles in advance that accommodate the maximum correction needs of any group, enabling efficient parallel processing of multiple beams without requiring extended irradiation times for individual correction, thus maintaining both accuracy and throughput.
Data Source
AI summary
According to one aspect of the present invention, a multiple charged particle beam writing method includes: setting one of a plurality of weighting coefficients, for each beam of multiple charged particle beams according to arrangement positions of the multiple charged particle beams; and correcting, in a case where multiple writing is performed on a same position of a target object as a writing target with a plurality of beams at different arrangement positions, two or more kinds of weighting coefficients being set for the plurality of beams, among the multiple charged particle beams, a dose of a beam concerned obtained in advance, using the two or more kinds of weighting coefficients of the plurality of beams with which writing is performed on the position, for each beam of the plurality of beams with which the position is irradiated.