Multi Beam Writing Apparatus Beam Shape Correction
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Solution Overview
Problem
Multi-beam writing apparatuses face challenges in achieving precise beam shape adjustment, leading to residual displacement errors that increase writing time and reduce throughput due to large correction doses required for ideal beam shape formation.
Innovation Solution
A multi-charged particle beam writing apparatus with a shaping aperture array plate, blanking aperture array plate, beam shape measurement unit, adjustment calculator, correction map generation unit, and controller, which measures and adjusts the reduction ratio and rotation angle of the multi-beam to correct beam shape distortions by optimizing irradiation amounts through a correction map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If beam adjustment is performed through lens excitation adjustment and beam alignment to achieve desired reduction ratio and rotation angle, then beam shape can be corrected, but residual displacement from ideal shape remains requiring large correction doses that increase writing time and reduce throughput
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction data in a correction map that compensates for beam shape deviations. Instead of performing real-time adjustments during writing, the system pre-processes the correction information based on measured beam shapes and reduction ratios, then applies these corrections during writing to minimize residual displacements and reduce correction doses.
Solution Approach 2:
The patent implements feedback by measuring the actual beam shape using a beam shape measurement unit, comparing it with the ideal beam shape, and using this information to generate appropriate correction maps. This closed-loop feedback mechanism ensures that corrections are based on actual measured deviations rather than theoretical calculations alone, improving accuracy while optimizing correction doses.
2Manufacturing precision
If large correction doses are applied to correct residual displacement errors, then beam shape accuracy improves, but writing time increases and throughput decreases
Solution Approach 1:
The correction map is generated in advance by pre-calculating the optimal correction doses based on measured beam shapes and reduction ratios. This preliminary calculation identifies the minimum necessary correction doses to achieve desired accuracy, preventing the need to apply excessively large correction doses during actual writing operations.
Solution Approach 2:
The system dynamically adjusts correction parameters based on the measured beam shape characteristics and reduction ratio. By changing the correction map parameters according to actual beam conditions rather than using fixed correction values, the system achieves accurate corrections with minimized doses, reducing writing time while maintaining precision.
3Productivity
If multi-beam writing is used to increase throughput, then writing speed improves, but beam shape control becomes more complex making precise adjustment difficult
Solution Approach 1:
The patent segments the beam shape correction problem into independent per-beam corrections. Instead of attempting to control the entire multi-beam system as a single complex entity, the system measures and corrects each beam's shape independently using individual correction data stored in the correction map, simplifying the control mechanism while maintaining overall pattern accuracy.
Solution Approach 2:
The system creates a correction map that serves as a template or copy of the ideal beam shape characteristics. This correction map is then applied consistently across all beams in the multi-beam system, providing a standardized approach to beam shape control that reduces operational complexity while maintaining precision across multiple beams.
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 solution allows for precise adjustment of the multi-beam's reduction ratio and rotation angle, reducing residual displacement errors and minimizing the correction dose, thereby enhancing writing accuracy and increasing throughput by optimizing the beam shape correction process.
Implementation Method 1
a beam shape measurement unit for measuring a first beam shape of the multi-beam based on a beam current of each beam of the multi-beam or an intensity of charged particles reflected from a reflection mark provided on the stage
Data Source
AI summary
In one embodiment, a multi charged particle beam writing apparatus includes a measurement unit measuring a first beam shape of a multi-beam based on a beam current of each beam of the multi-beam or an intensity of charged particles reflected from a reflection mark provided on a stage, an amounts of adjustment calculator calculating amounts of adjustment of a reduction ratio and a rotation angle of the multi-beam based on the first beam shape, a correction map generation unit generating a first correction map in which an amount of displacement is defined that is obtained for each beam of the multi-beam based on a difference between a beam shape based on the amounts of adjustment and the first beam shape, a writing data processor generating shot data in which an amount of irradiation with each beam of the multi-beam is defined by converting writing data in which information regarding a graphic pattern to be written is defined, and correcting the amount of irradiation with each beam defined in the shot data based on the first correction map, and a controller controlling the reduction ratio and rotation angle of the multi-beam based on the amounts of adjustment.