Multi-Beam Dose Reshaping for Lithography Throughput
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Solution Overview
Problem
Charged-particle multi-beam writing apparatuses face limitations in maximizing exposure dose and throughput due to constraints in current density and dose manipulation techniques, leading to issues with feature size accuracy and uniformity, particularly in scanning stripe exposure methods.
Innovation Solution
A method to recalculate patterns by reshaping pattern elements with assigned doses to align with a nominal dose, using a predefined dose slope function to adjust exposure doses uniformly across the pattern, thereby optimizing the writing process for charged-particle multi-beam writing apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dose manipulation techniques are used to adjust exposure doses, then feature size accuracy can be improved, but throughput is reduced due to non-linearity effects and contrast issues
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing dose-to-size mapping data before the actual writing process. The system creates a lookup table that maps desired feature sizes to required exposure doses, eliminating the need for real-time dose manipulation during writing. This pre-computation approach resolves the contradiction by preparing correction data in advance, allowing fast writing without non-linearity effects while maintaining feature size accuracy.
Solution Approach 2:
The patent substitutes the mechanical/dose-manipulation system with a data-driven approach. Instead of physically manipulating exposure doses during writing (which causes non-linearity effects), the system uses pre-computed mapping data to directly determine exposure parameters. This replacement of dose manipulation with lookup-based dose determination eliminates contrast issues and non-linearity effects while maintaining throughput.
2Productivity
If current density is increased to improve write performance, then productivity increases, but feature size uniformity deteriorates due to dose manipulation limitations
Solution Approach 1:
The patent uses preliminary action to pre-compute the relationship between exposure dose and feature size at different current densities. By storing this mapping data in advance, the system can quickly determine the appropriate dose for maintaining feature size uniformity without manipulating doses during high-speed writing, thus resolving the contradiction between write performance and feature size uniformity.
Solution Approach 2:
The patent applies parameter changes by utilizing pre-computed mapping data that accounts for variations in current density. The system selects appropriate exposure parameters from the stored mapping based on the actual writing conditions, allowing it to maintain feature size uniformity across different current densities without real-time dose manipulation, thereby improving both productivity and uniformity.
3Manufacturing precision
If dose adjustments are made to correct feature sizes, then manufacturing precision improves, but contrast issues and non-linearity effects worsen
Solution Approach 1:
The patent applies preliminary action by pre-computing dose-to-size mapping data that captures the relationship between exposure doses and resulting feature sizes under various conditions. This pre-computation is performed once and stored for reuse, eliminating the need for iterative dose adjustments during writing that cause contrast issues and non-linearity effects. The system simply looks up the appropriate dose from the pre-computed data, ensuring both feature size accuracy and writing reliability.
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 enhances productivity, improves lithography quality, reduces throughput losses, and maintains placement accuracy by ensuring consistent dose distribution, minimizing non-linear effects and edge roughness, and maintaining critical dimension uniformity.
Implementation Method 1
a structured beam composed of a plurality of beamlets is directed onto the target and moved along a path over the exposure region wherein between subsequent exposure steps the structured beam is shifted on the target
Data Source
AI summary
A method for re-calculating a pattern to be exposed on a target by means of a charged-particle multi-beam writing apparatus is presented. The pattern elements of a pattern, initially associated with a respective assigned dose, are recalculated in view of obtaining reshaped pattern elements which have a nominal dose as assigned dose. The nominal dose represents a predefined standard value of exposure dose to be exposed for pixels during a scanning stripe exposure within the multi-beam apparatus. For the pattern elements associated with an assigned dose deviating from the nominal dose, the pattern element is reshaped by determining a reshape distance from the value of the assigned dose using a predefined dose slope function forming a reshaped pattern element, whose boundary is offset with regard to boundary of the initial pattern element by an offset distance equaling said reshape distance, assigning the nominal dose to the reshaped pattern element, and replacing the pattern element by the reshaped pattern element.