Multi Charged Particle Beam Position Measurement Reproducibility
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Solution Overview
Problem
Accurate measurement of beam positions in multi-beam writing is challenging due to the small current per beam and weak signal strength, leading to decreased measurement accuracy and increased time required to measure numerous beams.
Innovation Solution
A method and apparatus that set measurement points and beam regions within an irradiation area, using a minimum number of beams necessary for reproducibility, to measure beam positions efficiently while maintaining dimensional accuracy, involving a multi-charged particle beam writing apparatus with a stage, emitter, aperture member, blanking plate, and measurement units to acquire and set these points and regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement is performed using all multi-beams, then measurement accuracy is improved, but measurement time increases significantly
Solution Approach 1:
The patent divides the measurement task into segments by selecting only necessary measurement points and using only the minimum number of beams required for adequate measurement reproducibility. Instead of measuring all beams at all points, the method segments the beam set into groups where a subset suffices for achieving the required measurement accuracy, thereby reducing total measurement time while maintaining precision.
Solution Approach 2:
The patent applies partial action by performing measurement with a partial set of beams (minimum number required) rather than all available beams. By determining the minimum number of beams needed to achieve acceptable measurement reproducibility, the system performs sufficient measurement action without the excess of using all beams, thus reducing measurement time while maintaining adequate accuracy.
2Loss of time
If number of beams for measurement is reduced, then measurement time is decreased, but measurement reproducibility deteriorates
Solution Approach 1:
The patent determines the minimum number of beams required to achieve acceptable measurement reproducibility. This partial action approach uses just enough beams to maintain reliability without the excess of using all beams, thereby reducing measurement time while preserving adequate measurement quality.
Solution Approach 2:
The patent changes the parameter of beam number from a fixed value (all beams) to a variable value (minimum required beams). By dynamically adjusting the number of beams used for measurement based on reproducibility requirements, the system optimizes the balance between measurement time and reliability, using fewer beams only when sufficient for achieving the required measurement quality.
3Illumination intensity
If current per beam is increased, then signal strength is improved, but beam current distribution uniformity deteriorates
Solution Approach 1:
The patent merges multiple beam signals at measurement points to achieve adequate signal strength. By combining the current from multiple beams (rather than increasing the current of a single beam), the system maintains the signal strength needed for reliable measurement while preserving the uniform current distribution characteristic of multi-beam systems.
Data Source
AI summary
A method of measuring beam positions of multi charged particle beams includes acquiring a number of multi charged particle beams needed for the measurement reproducibility of a current amount to be within the range of an allowable value. The method further includes setting measurement points depending on a desired dimensional accuracy value in an irradiation region irradiated by the whole of the multi charged particle beams, and setting, for each of a plurality of measurement points, a beam region, including a measurement point of measurement points irradiated by a plurality of beams whose number is the number of beams needed for the measurement reproducibility in the multi charged particle beams. Further, the method includes measuring, for each of a plurality of measurement points, the position of a measurement point concerned in a plurality of measurement points by using a plurality of beams of a corresponding beam region.