Active Fluid Damper for Stage Vibration Control in Metrology
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor metrology and inspection systems are sensitive to vibrations from external and internal sources, leading to adverse effects on evaluation results and reduced throughput due to the need to wait for vibrations to dissipate after stage movement.
Innovation Solution
An actively controlled damper using a pair of parallel plates with a fluid of variable viscosity, such as magnetorheological or electrorheological fluid, is employed, where a controller adjusts the viscosity by applying a current or electromagnetic field to the fluid to alter damping properties based on stage movement, thereby reducing vibrations and simplifying the control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive vibration isolation is used, then vibrations are reduced, but the system cannot actively respond to varying vibration conditions during stage movement
Solution Approach 1:
The damper transitions from a passive static system to an active dynamic system by using variable viscosity fluid whose damping characteristics can be changed in real-time. The controller adjusts the viscosity of the magnetorheological or electrorheological fluid based on stage movement conditions, enabling the system to adapt its vibration damping properties dynamically rather than relying on fixed passive isolation characteristics.
Solution Approach 2:
The invention changes the physical parameter of the damping fluid from constant viscosity to variable viscosity. By applying electromagnetic fields or currents to the magnetorheological or electrorheological fluid, the viscosity parameter can be rapidly adjusted to match different operational conditions, allowing the system to optimize vibration reduction across varying stage movement scenarios.
2Object-affected harmful factors
If complex feedback control systems are used, then vibration control is improved, but system complexity increases
Solution Approach 1:
The damper system uses the stage movement information already available in the metrology system to automatically adjust its damping characteristics. The controller receives stage movement signals and autonomously modulates the fluid viscosity without requiring external feedback sensors or complex control algorithms, enabling the system to self-regulate based on its own operational state.
Solution Approach 2:
The invention replaces complex mechanical feedback control mechanisms with a more straightforward electromagnetic control system. Instead of using mechanical sensors, linkages, and feedback loops, the system uses electromagnetic fields to directly modify the fluid properties based on electrical signals from the stage controller, simplifying the overall control architecture.
3Object-affected harmful factors
If damping is increased during stage movement, then vibrations are reduced, but measurement throughput decreases due to waiting for vibration dissipation
Solution Approach 1:
The damper operates in periodic cycles, switching between high-damping and low-damping modes synchronized with the stage movement pattern. During stage acceleration and positioning, the damper provides high damping to suppress vibrations. During measurement phases when the stage is stationary, the damper reduces damping to minimize vibration isolation effects, allowing measurements to proceed without waiting for vibration dissipation.
Solution Approach 2:
The system dynamically adjusts damping levels in real-time rather than maintaining a constant damping state. By coordinating the damping adjustments with the stage movement cycle, the system provides strong vibration suppression when needed while minimizing interference during measurements, thereby maintaining high throughput without compromising vibration control effectiveness.
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 solution effectively reduces vibrations experienced by the semiconductor metrology or inspection system, increasing damping during stage acceleration to dampen low-frequency excitation and decreasing damping during stationary or constant-speed movement to isolate higher frequencies, thus enhancing system throughput and accuracy without the need for complex feedback systems.
Implementation Method 1
The fluid may be a magnetorheological fluid or an electrorheological fluid in which the viscosity of the fluid is variable based on the electromagnetic field or current through the fluid
Implementation Method 2
The fluid may be a magnetorheological fluid or an electrorheological fluid in which the viscosity of the fluid is variable based on the electromagnetic field or current through the fluid
Data Source
AI summary
A damper for a semiconductor metrology or inspection system includes a pair of parallel plates with a fluid with a variable viscosity retained between plates. At least one wire is disposed between the plates, which may include one or more sets of lands and grooves. In some implementations, both plates include intermeshed lands and grooves. A controller is configured to provide a current to the at least one wire in order to adjust an electromagnetic field or a current through the fluid. The fluid may be a magnetorheological fluid or an electrorheological fluid in which the viscosity of the fluid is variable based on the electromagnetic field or current through the fluid. The controller varies the current applied to the wire to adjust the viscosity of the fluid to alter the damping of the semiconductor metrology or inspection system based on movement of the stage.