Projection Objective With Temperature-Compensated Electrostrictive Actuation
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Solution Overview
Problem
Existing projection exposure apparatuses face challenges in achieving high resolution and accuracy due to stringent imaging aberrations, particularly in EUV and DUV systems, where passive and active correction mechanisms are sought to address these issues.
Innovation Solution
Incorporation of an optical device with an electrostrictive actuator deformable by control voltage, connected to a temperature sensor, to influence the surface shape of optical elements, allowing for precise correction of imaging aberrations by measuring and compensating for temperature-dependent influences using a control device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive correction mechanisms are used to address imaging aberrations, then device complexity is reduced, but manufacturing precision and setting accuracy deteriorate
Solution Approach 1:
The patent employs active correction mechanisms with deformable mirrors that can dynamically adjust their surface shape in response to detected wavefront aberrations. This dynamic capability allows the system to adapt to varying optical conditions and achieve high precision correction, contrasting with static passive correction elements.
Solution Approach 2:
The system incorporates wavefront sensors that continuously measure optical aberrations and feed this information back to control actuators that adjust the deformable mirror surface. This closed-loop feedback mechanism enables real-time correction of imaging aberrations with high accuracy, resolving the contradiction between complexity and precision.
2Manufacturing precision
If active correction mechanisms are used to improve imaging precision, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The correction system is divided into discrete functional modules: wavefront sensors for detection, control electronics for processing, and distributed actuators for correction. This segmentation allows each component to be optimized independently and simplifies the overall system architecture despite the active correction capability.
Solution Approach 2:
The deformable mirror serves multiple functions: it acts as both an optical element for beam steering and a correction element for wavefront aberrations. This multi-functionality reduces the need for separate dedicated correction components, thereby managing system complexity while maintaining high precision.
3Device complexity
If temperature-dependent influences are not compensated, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
Temperature sensors are integrated into the actuator system to monitor thermal conditions. This temperature data is fed back to the control system, which compensates for temperature-dependent variations in actuator performance, thereby maintaining measurement precision without requiring overly complex compensation hardware.
Solution Approach 2:
The control system adjusts actuator driving parameters based on measured temperature conditions. By dynamically changing operational parameters rather than hardware configuration, the system achieves temperature compensation with minimal additional complexity while preserving measurement accuracy.
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
Enables high-accuracy correction of imaging aberrations in projection exposure apparatuses, enhancing resolution and accuracy by accounting for temperature-related effects on the electrostrictive actuator's performance.
Implementation Method 1
at least one electrostrictive actuator, which is deformable by a control voltage being applied
Implementation Method 2
A temperature sensor either directly attached to the optical device or in near proximity
Data Source
AI summary
A projection exposure apparatus comprises a projection objective, and the projection objective comprises an optical device, wherein the optical device comprises an optical element having an optically effective surface and an electrostrictive actuator. The electrostrictive actuator is deformable by a control voltage being applied. The electrostrictive actuator is functionally connected to the optical element to influence the surface shape of the optically effective surface. A control device supplies the electrostrictive actuator with the control voltage. A measuring device is configured, at least at times while the electrostrictive actuator influences the optically effective surface of the optical element, to measure directly and/or to determine indirectly the temperature and/or a temperature change of the electrostrictive actuator and/or the surroundings thereof to take account of a temperature-dependent influence during driving of the electrostrictive actuator by the control device.