Adaptive Optical Element Assembly for Precise Actuator Positioning
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Solution Overview
Problem
The production of extremely fine structures in microlithographic projection exposure apparatuses is hindered by complex and error-prone manufacturing processes of adaptive optical elements, particularly due to mechanical and electrical tolerances of solid-state actuators, which are often compensated with adhesives prone to moisture absorption and release, leading to deviations and thermal aberrations.
Innovation Solution
The use of bores in the substrate to receive and affix solid-state actuators via insertion elements, allowing precise positioning and robust attachment, with optional spacers and sealing mechanisms to maintain consistency and reduce mechanical stress, enabling controlled deformation of the optically effective surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is used to fasten solid-state actuators to the adaptive optical element, then the actuators can be attached to the substrate, but mechanical and electrical tolerances cannot be compensated and moisture absorption leads to deviations
Solution Approach 1:
The patent introduces a specialized mounting structure that acts as an intermediary between the solid-state actuator and the substrate. This mounting structure includes precision-machined reference surfaces and alignment features that mediate the connection, replacing the inadequate adhesive bonding. The intermediary structure provides both mechanical support and precise positioning, eliminating the dual problems of attachment reliability and positioning precision that arise with adhesive alone.
Solution Approach 2:
The mounting structure is segmented into distinct functional components: alignment features for positioning, reference surfaces for mounting, and integration interfaces for connecting the actuator to the substrate. This segmentation allows each component to optimize its specific function - alignment features handle positioning precision while reference surfaces handle attachment reliability - rather than relying on a single adhesive layer to perform both functions poorly.
2Ease of manufacture
If adhesive is used for joining actuators, then attachment is achieved, but adhesive gaps and moisture absorption cause deviations over service life
Solution Approach 1:
The mounting structure serves as a stable intermediary that eliminates the need for adhesive layers prone to moisture absorption. It provides a rigid, moisture-resistant connection path from the actuator through the mounting structure to the substrate, maintaining structural stability over the service life without the degradation issues associated with adhesive bonding.
Solution Approach 2:
The mounting structure utilizes composite construction combining materials with different properties - rigid materials for structural stability and moisture resistance, combined with precision-machined features for positioning. This composite approach achieves both ease of manufacture through modular assembly and long-term structural stability resistant to environmental degradation.
3Adaptability or versatility
If layer-by-layer production is used for adaptive mirrors, then complex structures can be built, but the production process becomes complex and error-prone
Solution Approach 1:
The mounting structures are pre-fabricated with integrated alignment features and reference surfaces before actuator assembly. This preliminary action creates ready-to-use mounting components that simplify the final assembly process, reducing production complexity while maintaining the ability to accommodate different actuator configurations and optical element designs.
Solution Approach 2:
The production process is segmented into independent modules: mounting structure fabrication, actuator assembly, and final integration. This segmentation allows each module to be optimized and manufactured separately with high precision, then assembled systematically, reducing overall production complexity while maintaining configurability for different optical element requirements.
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
Facilitates easier and more reproducible assembly of solid-state actuators, reduces mechanical deviations, and maintains structural integrity, thereby enhancing image position accuracy and quality by compensating for imaging aberrations.
Implementation Method 1
an adaptive mirror with at least one actuator, such as a solid-state actuator made of a piezoelectric material or ferroelectric material or electrostrictive material or magnetostrictive material, wherein for example an electric field of locally varying strength is generated across the piezoelectric layer by applying a voltage to electrodes arranged on both sides of the piezoelectric layer
Data Source
AI summary
An adaptive optical element for a microlithographic projection exposure apparatus, comprising: a substrate; an optically effective surface; and at least one solid-state actuator for at least partial deflection or deformation of the optically effective surface. At least one bore extends through at least regions of the substrate. An insertion element comprises the at least one solid-state actuator. The insertion element is in the bore so that the at least one solid-state actuator is affixed at a predetermined position within the bore.