Mirror Array Coating Zones for Angle-Dependent Reflectivity Control
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Solution Overview
Problem
Existing microlithography technologies face challenges in controlling layer thickness and composition with high spatial resolution and uniformity, particularly in optical elements like mirrors, to ensure high transmission and uniformity across varying angles of incidence, especially in extreme ultraviolet (EUV) and deep ultraviolet (DUV) ranges.
Innovation Solution
A method for producing optical elements, such as microlithographic mirrors, involves spatially resolved selection and treatment of coating material to create zones with defined layer thickness and composition, allowing for precise control of layer profiles and compositions even in small zones (0.1 mm to 2 cm) using techniques like masking, tempering, and selective charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coating methods are used to deposit layers on mirror substrates, then coating material is applied uniformly across the substrate, but it is difficult to create zones with different layer thickness and composition with high spatial resolution
Solution Approach 1:
The patent segments the coating process into multiple sequential coating passes, where each pass deposits coating material on different zones of the substrate. By dividing the substrate into multiple zones and applying coating material selectively in different passes, the method achieves precise control of layer thickness and composition in each zone without requiring complex real-time spatial control mechanisms.
Solution Approach 2:
The patent employs preliminary action by using masks to predefine the zones that will receive coating material in each coating pass. The masks are prepared in advance to block or allow coating material deposition on specific substrate regions, enabling precise spatial control of layer properties before the actual coating deposition occurs.
2Adaptability or versatility
If the optical system is designed for high numerical aperture and pupil filling, then the angle of incidence varies significantly, but maintaining high transmission and uniformity becomes difficult
Solution Approach 1:
The patent applies local quality by creating zones with different layer thickness and composition tailored to specific angular ranges. Each zone's coating properties are optimized for the local angle of incidence characteristics, allowing the optical system to maintain high transmission and uniformity across a wide range of angles by having different regions optimized for their respective angular conditions.
3Manufacturing precision
If zones of different layer thickness are created to control reflectivity, then optical performance is improved, but the coating process becomes more complex and time-consuming
Solution Approach 1:
The patent maintains continuity of useful action by performing multiple coating passes on the same substrate without removing or replacing it between passes. The substrate remains in place while different zones receive coating material in sequential passes, eliminating the need for repeated substrate handling, masking, and repositioning operations that would otherwise interrupt the coating process and reduce productivity.
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 enables precise control of reflectivity and optical performance by creating zones with varying layer thickness and composition, enhancing the optical system's performance and adaptability to different angles of incidence.
Implementation Method 1
at least one substrate is supplied with coating material from at least one source for depositing in each case a layer system on the substrate
Implementation Method 2
The spatially resolved selection of the coating material may comprise partially blocking out the coating material, in particular via a mask
Data Source
AI summary
In a method for producing an optical element, at least one substrate is supplied with coating material from at least one source for depositing a respective layer system on the substrate. A plurality of zones (111, 112, 121, 122) that are laterally adjacent to one another in at least one predefined direction and each have a defined layer thickness profile and a defined layer composition are formed by targeted spatially resolved selection and/or treatment of the deposited coating material and/or the substrate. These zones differ from each other in their layer thickness profiles and/or their layer compositions. The average dimension of each of the zones in the predefined direction is between 0.1 mm and 2 cm. The optical element is a mirror array with plural mirror elements. For different substrates of this mirror array, mutually different layer thickness profiles and/or layer compositions of the respectively deposited layer system are generated.