Electron Beam Tracking Control for High-Speed Stage Movement
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Solution Overview
Problem
Conventional electron beam writing systems face throughput reduction and frequent operation abortion due to inappropriate stage movement speed and electron beam deflection range, leading to deviations in the irradiated area, which are not effectively addressed by existing methods that require trial writing operations or reduced stage speed.
Innovation Solution
A tracking control method that calculates an optimal number of subfield sections by dividing the time required for all beam shots by a time unit and the number of beam shots by the number of sections, allowing real-time adjustment of beam shots and shifting operations between sections based on stage movement, ensuring accurate and continuous electron beam deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the stage moves continuously at high speed to improve throughput, then productivity increases, but the electron beam deflection range becomes inappropriate causing tracking abnormalities and operation abortion
Solution Approach 1:
The patent divides the subfield into multiple divided subfields based on the stage movement distance during the beam shot period. This segmentation allows the system to handle tracking control in smaller, manageable intervals, preventing tracking abnormalities even at high stage speeds. The subfield division number calculation ensures that each divided subfield corresponds to an appropriate stage movement range that the main deflector can accurately track.
Solution Approach 2:
The patent dynamically adjusts the subfield division strategy based on real-time parameters including stage speed, beam shot period, and deflector characteristics. By calculating the optimal number of divided subfields according to the formula involving these dynamic parameters, the system adapts to varying operating conditions while maintaining tracking stability and preventing operation abortion.
2Reliability
If the subfield is divided into multiple sections to prevent tracking abnormalities, then reliability improves, but the complexity of control calculations and operations increases
Solution Approach 1:
The patent performs preliminary calculation of the subfield division number before actual writing operations begin. By pre-calculating the optimal division based on stage speed, beam shot period, and deflector characteristics, the system establishes appropriate control parameters in advance, simplifying the real-time control process and reducing operational complexity while ensuring tracking stability.
3Reliability
If the stage speed is reduced to maintain appropriate beam deflection range, then tracking stability improves, but productivity decreases
Solution Approach 1:
The patent enables the system to maintain high stage speeds while ensuring tracking accuracy by dynamically calculating the appropriate subfield division number. This allows the stage to move continuously at optimal speeds for productivity, while the divided subfield approach ensures that each beam shot operation covers an appropriate distance that the main deflector can accurately track, thus maintaining both speed and precision.
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 method enables reliable real-time calculation of optimal subfield divisions, reducing the likelihood of operation abortion and maintaining high throughput by ensuring accurate and continuous electron beam deflection, even at high shot densities.
Implementation Method 1
a main deflector deflects an electron beam to ensure that a region in a subfield of a mask blank placed on the stage that continuously moves is irradiated with the electron beam
Data Source
AI summary
Control data for a main deflector is calculated based on position data that specifies the position of a region to be irradiated with the electron beam on the subfield, data on the number of all beam shots on the subfield, data on a time required for all the beam shots, and stage data that specifies the position of the stage. When the number of beam shots on one of the divided subfield sections reaches the obtained number of the beam shots on each of the divided subfield sections, a writing process proceed to a writing operation to be performed on another one of the divided subfield sections based on the direction of the movement of the stage.