Charged Particle Beam Writing Apparatus Dose Correction
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Solution Overview
Problem
Conventional electron beam writing methods require excessive irradiation time due to uniform dose calculation across all regions, including those far from the figure end, leading to longer writing times and potential dose shortages from incomplete convergence.
Innovation Solution
A charged particle beam writing apparatus and method that iteratively calculates and corrects dose coefficients for each small region, using different equations based on proximity to the figure end or inside, to optimize dose distribution and reduce convergence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uniform dose calculation is used for all regions including those far from the figure end, then dose distribution is simplified, but writing time becomes excessively long
Solution Approach 1:
The patent divides the writing region into multiple small regions (mesh-like divisions) and performs iterative calculation for each region. This segmentation allows the system to calculate doses locally rather than uniformly across the entire region, reducing unnecessary calculations in areas far from the figure end while maintaining dose accuracy where needed.
Solution Approach 2:
The patent applies different dose calculation approaches based on the local characteristics of each region. Regions close to the figure end receive more precise iterative dose calculation, while regions far from the figure end use simplified calculations. This local differentiation optimizes writing time without compromising critical dose distribution accuracy.
2Manufacturing precision
If iterative calculation is performed for all regions, then dose accuracy is improved, but calculation time increases
Solution Approach 1:
The patent performs preliminary identification of small regions that are close to the figure end before performing iterative calculations. By pre-determining which regions require precise iterative dose calculation and which can use simplified methods, the system avoids unnecessary iterative calculations in distant regions, significantly reducing convergence time while maintaining accuracy where it matters.
Solution Approach 2:
The patent applies iterative dose calculation selectively only to regions that require it (those close to the figure end), rather than performing excessive iterative calculations across all regions. This partial application of the computationally intensive method optimizes the balance between dose accuracy and calculation time.
3Manufacturing precision
If dose is set to ensure threshold value at figure end, then pattern resolution is maintained, but other regions receive excessive dose
Solution Approach 1:
The patent calculates doses locally for each small region based on its specific characteristics and distance from the figure end. This local dose optimization ensures that regions close to the figure end receive sufficient dose for pattern resolution, while regions far from the figure end receive appropriate reduced doses, eliminating excessive energy delivery without compromising critical pattern quality.
Data Source
AI summary
A charged particle beam writing apparatus according to an embodiment, includes a dose coefficient calculation unit to calculate an n-th dose correction coefficient in iterative calculation of a charged particle beam to be shot in a small region concerned by the iterative calculation, for each small region of small regions made by virtually dividing into mesh-like regions, a change rate calculation unit to calculate, for each small region, a rate of change from an (n-1)th dose correction coefficient to the n-th dose correction coefficient calculated in the iterative calculation, as an n-th change rate, a correction calculation unit to correct, for each small region, the n-th dose correction coefficient by using the n-th change rate, and a dose calculation unit to calculate, for each small region, a dose of a charged particle beam to be shot in a small region concerned by using the n-th dose correction coefficient corrected.