Multi Beam Writing Apparatus Elastic Rate Correction
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Solution Overview
Problem
In multi-beam writing, the space charge effect causes dynamic changes in the number of ON beams and beam current, leading to focus deviation and position deviations in the writing pattern, making it difficult to correct these issues in real-time.
Innovation Solution
A multi-charged particle beam writing apparatus and method that divides the irradiation of each beam into multiple times with different irradiation times, using a divided shot data generation unit and individual blanking systems to adjust the beam pattern and correct the elastic rate of the image, with a lens system to correct the focus and position deviations based on the number of ON beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are emitted simultaneously in multi-beam writing to increase throughput, then productivity is improved, but space charge effect causes focus deviation and position deviation worsening manufacturing precision
Solution Approach 1:
The patent divides a single shot of multiple beams into multiple divided shots, where each divided shot contains a subset of the original beams. This segmentation reduces the number of simultaneous beams in each shot, thereby reducing the space charge effect while maintaining overall productivity through multiple passes.
Solution Approach 2:
The patent performs preliminary calculation of elastic rate correction values based on the number of ON beams before actual writing. This allows the system to pre-determine the appropriate correction values for each divided shot, enabling real-time correction without delaying the writing process.
2Manufacturing precision
If the number of ON beams changes dynamically during irradiation to control dose, then manufacturing precision is improved, but space charge effect varies causing difficulty in correction worsening device complexity
Solution Approach 1:
The patent changes the elastic rate parameter dynamically based on the number of ON beams in each divided shot. By calculating and applying appropriate elastic rate correction values for each shot configuration, the system maintains precise dose control while adapting to varying space charge effects.
Solution Approach 2:
The patent implements a feedback mechanism where the number of ON beams is monitored and used to select appropriate elastic rate correction values. This feedback loop ensures that the correction system adapts to the actual beam configuration, maintaining precision without requiring overly complex real-time calculation systems.
3Manufacturing precision
If elastic rate correction is applied for each divided shot based on number of ON beams, then manufacturing precision is improved, but device complexity increases due to additional correction mechanisms
Solution Approach 1:
The patent performs preliminary calculation of elastic rate correction values before the actual writing process. By pre-calculating these values based on the expected number of ON beams in each divided shot, the system reduces the computational burden during real-time operation and simplifies the correction mechanism.
Solution Approach 2:
The patent adjusts the elastic rate parameter based on the number of ON beams, using a relatively simple correction mechanism that modifies an existing parameter rather than introducing complex new systems. This approach maintains precision while minimizing added complexity.
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 effectively corrects position and focus deviations caused by the space charge effect, maintaining consistent beam current and pattern accuracy during multi-beam writing by adjusting the irradiation times and blanking control for each divided shot.
Implementation Method 1
In a charged particle beam, such as an electron beam, repulsion occurs, on the beam path, among particles having electric charge and thereby the beam path changes. The effect of this causes a space charge effect that becomes large in proportion to the beam current (the number of particles).
Data Source
AI summary
A multi charged particle beam writing apparatus includes a divided shot data generation unit to generate, for each shot of multi beams of charged particle beams, data for plural times of divided shots such that irradiation for one shot of each beam is divided into plural times of divided shots each having a different irradiation time, an individual blanking system to provide blanking control individually for each of multi beams, based on the data for plural times of divided shots, an elastic rate correction value acquisition unit to acquire, for each of plural times of divided shots, an elastic rate correction value for correcting an elastic rate of an image of the whole multi beams, depending upon the number of ON-beams of the multi beams, and a lens to correct, for each divided shot, the elastic rate of the image of the whole multi beams by using the correction value.