Charged-Particle Beam Writing Timing Control for Settling Time Reduction
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Solution Overview
Problem
The existing charged-particle beam writing techniques face challenges in achieving high accuracy and throughput due to the variation in deflection angle of the electron beam, which affects the shape, position, and size of the written pattern, and the need for a blanking mechanism to prevent sample irradiation during settling time, leading to potential inaccuracies and reduced throughput.
Innovation Solution
A charged-particle beam writing apparatus and method that control the timing of applying voltage to the sub deflector based on the termination time of irradiation, using timing control means and a control computer to determine the appropriate timing for voltage application, ensuring accurate pattern writing and improved throughput by optimizing the settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the voltage is applied to the sub deflector after a predetermined time elapses from the blanking start time, then the settling time is reduced, but the writing accuracy is degraded because pattern formation starts before the sub deflector output is stabilized
Solution Approach 1:
The invention applies voltage to the sub deflector at the blanking start time (preliminary action) rather than after a predetermined delay. This allows the deflector output to be stabilized before pattern formation begins, while the blanking mechanism prevents electron beam irradiation during the settling period, thus maintaining writing accuracy without losing throughput time.
2Productivity
If the electron beam is deflected at high speed to improve throughput, then the settling time becomes more critical, but the writing accuracy is reduced due to insufficient stabilization time
Solution Approach 1:
The voltage application to the sub deflector is performed at the blanking start time, allowing the deflector to stabilize its output before pattern formation. The blanking mechanism ensures the electron beam is blocked during this stabilization period, enabling high-speed deflection without compromising writing accuracy.
Solution Approach 2:
The invention converts the harmful effect of prolonged settling time (which reduces throughput) into a benefit by synchronizing voltage application with the blanking period. The settling time is effectively utilized without extending the total cycle time, as the blanking mechanism masks the settling period from the productive writing time.
3Productivity
If the voltage is applied to the sub deflector before the blanking start time, then the throughput is improved, but the writing accuracy is reduced because an unnecessary region is irradiated with the electron beam
Solution Approach 1:
The voltage is applied to the sub deflector exactly at the blanking start time, which is the optimal moment when the electron beam is already blocked. This timing ensures the deflector has sufficient time to stabilize before pattern formation without causing unnecessary irradiation of regions outside the intended pattern area.
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 reduces the settling time overhead, maintains writing accuracy, and enhances throughput by precisely controlling the voltage application to the sub deflector, ensuring the electron beam is stabilized before pattern formation, thus improving the overall writing process efficiency.
Implementation Method 1
a charged-particle beam is deflected by a main deflector and a sub deflector, which are disposed on the optical path of the charged-particle beam
Data Source
AI summary
A timing control circuit controls the timing for applying a voltage to a sub deflector when changing a position to be irradiated with the charged-particle beam. A control computer compares a target line width and a line width of a pattern written with the timing for applying voltage to the sub deflector changed, and determines appropriate timing for applying voltage to the sub deflector from a timing range corresponding to a predetermined allowable range of the difference between the target line width and the line width of the written pattern. The control computer then controls the timing control circuit based on the determined timing.