Dual Piezo Actuator for Continuous Optical Deflection
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Solution Overview
Problem
The existing linear drives for deflecting optical elements in projection exposure apparatuses for microlithography face inefficiencies due to the need for a pause during actuator changeover, which can result in undesired position alterations and loss of precision, especially when transitioning from maximum shearing to stepping mode.
Innovation Solution
The implementation of a manipulator system with two actuators, each controllable within specific ranges, allows for continuous deflection of the optical element by jointly or separately controlling the actuators based on predefined control ranges and conditions, ensuring minimal deflection in any direction without the need for pause, thus maintaining precision and reducing unwanted force inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single actuator is used for deflecting the optical element, then the device complexity is reduced, but the productivity is worsened due to the need for pause during actuator changeover
Solution Approach 1:
The manipulator is segmented into multiple actuators (first actuator and second actuator) that can operate independently and be switched between. This allows one actuator to be used while another is prepared or reset, eliminating the need for system pause during changeover and maintaining continuous productivity.
Solution Approach 2:
The system performs preliminary actions by preparing the second actuator in advance while the first actuator is still operational. This overlap in operation ensures that when switching is needed, the replacement actuator is already ready, eliminating idle time and maintaining continuous deflection capability.
2Adaptability or versatility
If actuator changeover is performed during maximum shearing, then the adaptability is improved, but the manufacturing precision is worsened due to undesired position alterations
Solution Approach 1:
The system cushions against position alterations by using multiple actuators that can share the load or compensate for each other during transition. The second actuator can be pre-positioned to match the current deflection state, preventing sudden position changes when switching from the first actuator at maximum shearing.
Solution Approach 2:
The control system acts as an intermediary that coordinates the transition between actuators. It manages the shearing force distribution and ensures smooth handover of the deflection task, preventing undesired position alterations during the changeover process.
3Productivity
If the optical element is deflected rapidly in any direction, then the productivity is improved, but the reliability is worsened due to loss of precision
Solution Approach 1:
The manipulator system is designed to be dynamic, allowing rapid switching between actuators and adaptive control of deflection speed. This dynamic capability enables the system to maintain precision during fast movements by adjusting control parameters in real-time based on the current operational state.
Solution Approach 2:
The system uses feedback control to monitor the deflection position and adjust the actuator commands accordingly. This ensures that even during rapid deflection in any direction, the optical element reaches the desired position with required precision, maintaining imaging performance while enabling high productivity.
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 enables continuous and precise deflection of the optical element without pauses, improving the imaging performance by allowing for direct and controlled movement in any direction, thereby addressing the inefficiencies of existing systems.
Implementation Method 1
the first actuator contains a first shear piezo and the second actuator contains a second shear piezo, wherein the optical element is deflectable via frictional engagement between the shear piezos and the inner mount and shearing of the shear piezos in the direction of the degree of freedom
Implementation Method 2
linear drives comprising piezo elements for example. The latter, triggered by a change in a voltage present at the piezo crystal, bring about expansion or shearing of the piezo crystal or a piezo stack
Implementation Method 3
the optical element is deflectable via frictional engagement between the shear piezos and the inner mount
Implementation Method 4
the first actuator contains a first stroke piezo and the second actuator contains a second stroke piezo, wherein the stroke piezos produce the frictional engagement between inner mount and shear piezos by expansion in a direction which is orthogonal to that of the degree of freedom
Data Source
AI summary
A projection exposure apparatus for microlithography includes an optical element actuatable by a first and a second actuator. The actuators are controlled via control intervals in such a way that a minimum deflectability predefined in accordance with a preselectable parameter is guaranteed at every point in time of the control.