Charged Particle Beam Vibration Damping with Dynamic Gain Control
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Solution Overview
Problem
Charged particle beam apparatuses face increased vibration due to the addition of correction devices, which reduces column rigidity and requires high-output actuators to effectively dampen vibrations, but existing solutions struggle to adjust feedback gain effectively, leading to insufficient damping.
Innovation Solution
A vibration damping system with a control device that includes a damping gain control unit and a saturation suppression unit to adjust feedback gain based on vibration detection signals, ensuring the damping mechanism operates within its maximum and minimum output values, thereby achieving optimal damping control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-output actuator is used to dampen vibration effectively, then vibration damping performance is improved, but the device size increases and may affect the electron source or column vibration
Solution Approach 1:
The feedback gain is dynamically adjusted based on the detected vibration level. When vibration exceeds a threshold, the gain is increased to provide stronger damping; when vibration is low, the gain is reduced. This dynamic adjustment allows the use of a compact actuator that can deliver high output when needed without constantly operating at high power levels that would require a larger device size.
Solution Approach 2:
The system changes the feedback gain parameter according to vibration conditions. The control device includes a feedback gain adjustment unit that modifies the gain based on detected vibration levels, allowing the same actuator to provide appropriate damping force across different operating conditions without requiring a high-output design for all scenarios.
2Reliability
If the feedback gain is increased to enhance damping effect, then vibration suppression is improved, but the actuator output may exceed maximum limits causing saturation
Solution Approach 1:
The system uses feedback control where the vibration detection unit continuously monitors column vibration and the control device adjusts the feedback gain based on detected vibration levels. This closed-loop feedback ensures the actuator output remains within optimal ranges, preventing saturation while maintaining effective damping when vibration occurs.
Solution Approach 2:
The feedback gain is dynamically adjusted based on real-time vibration detection. When vibration is detected above a threshold, the gain is increased to enhance damping; when vibration is below the threshold, the gain is reduced. This dynamic adjustment prevents the actuator from exceeding its maximum output capacity while ensuring sufficient damping effect when needed.
3Adaptability or versatility
If the column size is increased to accommodate correction devices, then functional capability is improved, but column rigidity decreases leading to increased vibration
Solution Approach 1:
Instead of relying solely on mechanical reinforcement of the column to maintain rigidity, the system substitutes a vibration damping mechanism using sensors and actuators. The vibration detection unit detects column vibrations, and the control device drives the actuator to apply counter-vibrations that cancel out the harmful vibrations, effectively compensating for the reduced mechanical rigidity caused by the larger column size.
4Productivity
If stage acceleration is increased to improve throughput, then productivity is improved, but driving reaction force increases causing more column vibration
Solution Approach 1:
The vibration detection unit continuously monitors column vibrations generated during stage acceleration. The control device processes these detection signals and adjusts the actuator output in real-time to counteract the vibrations caused by high-speed stage movement, enabling high throughput operation without compromising vibration control.
Solution Approach 2:
The feedback gain is dynamically adjusted based on vibration levels during stage operation. During high-acceleration phases that generate more vibration, the gain is increased to provide stronger damping. During low-acceleration phases, the gain is reduced. This dynamic response allows the system to maintain effective damping across varying productivity requirements.
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
The system provides effective damping control tailored to the device's situation and performance, preventing excessive output and ensuring maximum damping effect, even under varying disturbances.
Implementation Method 1
a vibration detection unit that detects vibration of the column
Implementation Method 2
a damping mechanism that applies vibration to the column to suppress the vibration of the column
Data Source
AI summary
A vibration damping system for a charged particle beam apparatus according to the present invention includes a column through which a charged particle beam passes, a vibration detection unit that detects vibration of the column, a damping mechanism that applies vibration to the column to suppress the vibration of the column, and a control device that controls the damping mechanism. The control device includes a damping gain control unit that amplifies a detection signal of the vibration detection unit with a set amplification factor and outputs an amplified detection signal as a control signal to the damping mechanism, and a saturation suppression unit that adjusts a feedback gain value of the damping gain control unit according to a detection signal of the vibration detection unit, a signal of the damping mechanism, and a maximum output value and a minimum output value of the damping mechanism.