Optical Assembly Actuator Segmentation for Fine-Setting Precision
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Solution Overview
Problem
Existing projection exposure apparatuses face challenges in achieving precise and flexible fine setting of optical elements due to thermal deformations and hysteresis effects in actuators, which complicate the correction of imaging aberrations and reduce controllability.
Innovation Solution
An optical assembly with at least three sections of actuators, comprising a first group for coarse actuation and a second group for fine actuation, controlled independently, allowing variable adjustment of the ratio between their deflections to adapt to different application situations, and utilizing transverse and longitudinal deformations of the actuator matrix to correct optical element alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single actuator is used for positioning optical elements, then the device complexity is low, but the manufacturing precision and fine setting capability are insufficient due to thermal deformations and hysteresis effects
Solution Approach 1:
The actuator is divided into multiple independent sections (first section, second section, third section) that can be controlled separately. This segmentation allows different parts of the actuator to perform different functions: coarse positioning and fine positioning, thereby improving manufacturing precision while managing device complexity through modular control
Solution Approach 2:
The controller dynamically switches between different actuator sections based on the required positioning precision. During coarse positioning, the first section is actively controlled while the second section is fixed; during fine positioning, the third section is activated. This dynamic allocation optimizes the precision-to-complexity ratio
2Manufacturing precision
If the actuator is divided into multiple sections for coarse and fine setting, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The actuator is segmented into multiple independently controllable sections, each responsible for specific positioning tasks. This allows the system to achieve high precision by activating only the necessary sections for each positioning phase, reducing the effective control complexity while maintaining high manufacturing precision
Solution Approach 2:
Instead of controlling all actuator sections simultaneously, the system uses partial action by activating only the required sections for each positioning phase. During coarse positioning, only the first section is controlled; during fine positioning, the third section is activated. This reduces control complexity while achieving the required precision
3Reliability
If actuators are used to correct imaging aberrations, then the imaging quality is improved, but thermal deformations and hysteresis effects reduce the reliability of fine setting
Solution Approach 1:
By dividing the actuator into multiple sections that can be independently controlled, the system can isolate the fine positioning function to a specific section (third section) that is less affected by thermal deformations. This segmentation allows the fine setting to be performed by a dedicated section, improving reliability despite the presence of harmful thermal effects in other parts of the actuator
Solution Approach 2:
The controller acts as an intermediary that compensates for thermal deformations and hysteresis effects by dynamically adjusting the control signals to different actuator sections. It coordinates between the coarse positioning section and fine positioning section, ensuring that thermal effects in one section do not compromise the reliability of fine setting in another section
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
Enhances imaging quality by improving actuator resolution and reducing hysteresis effects, enabling precise and flexible control of optical elements, even under thermal stress.
Implementation Method 1
The actuator (26.2, 26.3) is configured to deform the optical element (21) by way of a transverse contraction of the actuator (26.2, 26.3)
Implementation Method 2
a first layer of piezoactuators (27.1) serving for coarse setting and a second layer of piezoactuators (27.2) serving for fine setting
Implementation Method 3
changes in the controllability of the actuators on account of changing parameters for the physical effects underlying the actuator effect, for example for the electrostrictive, piezoelectric or magnetostrictive effect
Implementation Method 4
changes in the controllability of the actuators on account of changing parameters for the physical effects underlying the actuator effect, for example for the electrostrictive, piezoelectric or magnetostrictive effect
Implementation Method 5
They can also lead, in the manipulators themselves and for example in the actuators thereof, firstly to thermal deformations
Data Source
AI summary
An optical assembly for semiconductor lithography comprises an optical element and an actuator for deforming the optical element. The actuator is constructed from at least three sections, which include at least first and second group of sections that are controllable in each case via a controller are present. The first group serves for coarse actuation, and the second group serves for fine actuation. The controller is configured to control the groups independently of one another and the sections of a group jointly. The controller is furthermore configured to variably set the number of sections controlled jointly per group. Furthermore, the disclosure relates to a projection exposure apparatus equipped with the assembly, and to a method for controlling the optical assembly.