Piezoelectric Actuator Modules for Lithographic Lens Positioning
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Solution Overview
Problem
Conventional systems for positioning optical elements in lithographic apparatuses face challenges due to friction, stiction, and variable stiffness, which affect the accuracy and reliability of lens element positioning, and lack independent adjustment capabilities for lateral orientation, tip, and rotation.
Innovation Solution
A system utilizing piezoelectric actuator modules that apply combined forces perpendicular and parallel to elongated support structures to position optical elements within a lithographic apparatus, allowing for precise adjustment of longitudinal, lateral, and rotational positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a slide mechanism with mechanical actuators is used for positioning lens elements, then the positioning system can be mechanically simple, but the accuracy is degraded due to friction, stiction, and variable stiffness
Solution Approach 1:
The patent replaces mechanical actuators (screws, motors) with piezoelectric actuators that convert electrical signals directly to mechanical displacement. This substitution eliminates friction and stiction inherent in mechanical systems while providing high positioning accuracy through direct electromagnetic-to-mechanical energy conversion, resolving the contradiction between mechanical simplicity and positioning accuracy
Solution Approach 2:
The patent changes the physical state and properties of the support structures by using piezoelectric materials that exhibit controlled deformation in response to electrical fields. This parameter change enables precise control of lens element positions without the friction and stiffness variations characteristic of mechanical contact-based systems
2Object-affected harmful factors
If frictionless bearings like fluid bearings or magnetic levitation bearings are used, then friction and stiction are reduced, but stiffness becomes low or variable
Solution Approach 1:
The patent replaces frictionless mechanical bearings with piezoelectric actuators that provide both contactless positioning (eliminating friction) and active stiffness control through material properties and control algorithms. The piezoelectric elements maintain positional stability and stiffness without relying on mechanical contact or fluid dynamics
3Device complexity
If a single actuator per optical element is used, then the device complexity is reduced, but independent adjustment of lateral orientation, tip, tilt, or rotation is not possible
Solution Approach 1:
The patent segments the positioning function into multiple independent piezoelectric actuators (typically three or more) arranged around each optical element. This segmentation allows each actuator to control specific degrees of freedom (lateral position, tilt, rotation), enabling independent adjustment of all orientation parameters while maintaining a relatively simple overall device structure
Solution Approach 2:
The patent designs the piezoelectric actuator array to perform multiple functions simultaneously - controlling lateral position, tip angle, tilt, and rotation of optical elements using a unified actuation system. This multi-functionality approach allows a single actuator assembly to replace what would otherwise require separate mechanisms for each degree of freedom
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 solution achieves accurate and reliable positioning with low friction and high stiffness, enabling independent adjustment of optical elements, thereby improving the precision and reliability of optical element placement in lithographic apparatuses.
Implementation Method 1
Each of the one or more actuator modules includes at least one piezoelectric element configured to (i) apply a first force to the at least one elongated surface of the respective one of the one or more elongated support structures
Data Source
AI summary
A positioning system adjusts a position of an optical element within an optical device, such as a variable-zoom lens system. A frame supports the optical element, and an elongated surface of each of one or more elongated support structures supports the frame. The frame also supports one or more piezoelectric actuators that, respectively, engage one of the elongated support structures. A controller supplies a control signal to activate each of the one or more actuator modules. Upon activation, a piezoelectric element of each of the activated actuator modules applies a combination of a first force and a second force to an elongated surface of the respective elongated support structures to position the frame along the elongated surface. The combination of forces applied by the piezoelectric element advances the piezoelectric actuator module along the elongated support structure.