Mirror Element Curvature via Layer Stack Tension
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Solution Overview
Problem
The production of mirror elements for microlithographic projection exposure apparatuses in the EUV range faces challenges due to mechanical tensions generated during the layering process, which can deform the substrate and impair optical imaging properties, and requires precise adjustment of refractive power, often involving complex substrate design and tension compensation.
Innovation Solution
A method that utilizes the mechanical tension generated during the application of a layer stack to create a desired setpoint curvature and refractive power in the mirror element by adjusting the substrate's curvature and rigidity, allowing for targeted deformation and post-treatment to achieve the desired geometry, rather than relying on initial substrate design and tension compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical tension compensation layers are added to minimize substrate deformation, then optical imaging properties are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent converts the harmful mechanical tension generated during layer deposition into a beneficial curvature formation process. Instead of adding compensation layers to counteract tension, the invention utilizes the tension to deliberately bend the substrate into the desired curved shape, thereby achieving both optical precision and simplified device structure
Solution Approach 2:
The patent changes the physical state and mechanical properties of the substrate during the layer deposition process. By controlling the deposition parameters and substrate temperature, the mechanical tension is transformed into a controlled curvature, allowing the substrate to transition from a flat state to a desired curved configuration without additional compensation layers
2Manufacturing precision
If substrate design and tension compensation are performed to achieve desired refractive power, then optical properties are improved, but manufacturing complexity increases
Solution Approach 1:
The patent enables the layer stack itself to serve the dual function of optical reflection and mechanical curvature generation. The layer deposition process automatically generates the desired curvature through controlled tension application, eliminating the need for separate substrate design steps and compensation procedures
Solution Approach 2:
The patent merges the optical layer stack formation process with the mechanical curvature generation process. The same layer deposition that creates the reflective surface also generates the mechanical tension needed to form the desired curvature, combining two previously separate functions into a single integrated process
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 minimizes manufacturing complexity and enables the generation of mirror elements with precise refractive power and curvature, improving optical imaging properties while reducing the need for additional compensation layers, thus enhancing the efficiency of the microlithographic process.
Implementation Method 1
mechanical tensions are generated during the layering process... which mechanical tensions can lead to a deformation of the substrate
Implementation Method 2
the layer stack is formed so that a setpoint curvature of the mirror element sought for a predetermined operating temperature is generated by a bending force exerted by the layer stack
Data Source
AI summary
A method for producing a mirror element, in particular for a microlithographic projection exposure apparatus includes: providing a substrate (101, 102, 103, 104, 201, 202, 301, 302, 401, 402, 501, 502, 801, 901, 951, 961); and forming a layer stack (111, 112, 113, 114, 211, 212, 311, 312, 411, 412, 511, 512) on the substrate, wherein the layer stack is formed so that a setpoint curvature of the mirror element for a predetermined operating temperature is generated by a bending force exerted by the layer stack, wherein the substrate has a curvature deviating from the setpoint curvature of the mirror element prior to the formation of the layer stack, and wherein the bending force exerted by the layer stack is at least partly generated by virtue of a post-treatment for changing the layer tension of the layer stack.