Laser-Ablated Cooling Channels for Stable EUV Mirror Temperature Control
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Solution Overview
Problem
Current methods for producing temperature-regulating hollow structures in EUV projection exposure apparatuses face challenges in effectively counteracting flow-induced vibrations (FIVs) and achieving flexible, high-quality temperature regulation, which affects the heat transfer and stability of mirrors used in semiconductor technology.
Innovation Solution
The method involves a scanning trajectory with multiple scanning patterns and pattern jump paths to precisely ablate temperature-regulating hollow structures, allowing for flexible control and adaptation of the ablation process, including line-to-line, meandering, and sector scanning patterns, to minimize FIVs and enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ablation methods are used to produce temperature-regulating hollow structures, then the basic cooling function is achieved, but flow-induced vibrations (FIVs) occur and temperature regulation flexibility is limited
Solution Approach 1:
The patent applies local quality by creating hollow structures with specifically optimized geometries (circular, elliptical, polygonal cross-sections) and strategic positioning within the substrate. The hollow structures are designed with specific diameter ranges (0.1-10 mm) and wall thicknesses (0.01-1 mm) to locally enhance cooling efficiency while minimizing FIVs. The selective placement of multiple hollow structures at different locations allows targeted temperature control in regions most susceptible to thermal distortion.
Solution Approach 2:
The patent employs parameter changes by varying the geometric parameters of hollow structures (cross-sectional shape, diameter, length, wall thickness) and their spatial arrangement to optimize cooling performance. The hollow structures can have different orientations and configurations adapted to specific thermal load patterns. Process parameters such as laser power, scanning speed, and pulse duration are dynamically adjusted during ablation to achieve precise control over hollow structure formation and minimize vibrations.
2Ease of manufacture
If standard hollow structures are incorporated into the substrate, then cooling is provided, but process flexibility and manufacturing precision are compromised
Solution Approach 1:
The patent applies preliminary action through computer-aided design and simulation of hollow structure geometries and positions before the actual ablation process. The manufacturing process begins with digital modeling of the substrate and thermal load analysis to determine optimal hollow structure configurations. This preliminary planning enables precise control over the subsequent ablation process, ensuring that hollow structures are formed with accurate dimensions and positions while maintaining ease of manufacture through automated processing.
Solution Approach 2:
The patent replaces traditional mechanical drilling or machining methods with laser ablation technology. The laser beam delivers precise energy to the substrate material, vaporizing it layer by layer to form hollow structures with complex geometries that would be difficult or impossible to achieve mechanically. This substitution enables superior manufacturing precision with tighter tolerances, smoother surfaces, and greater design flexibility while maintaining ease of manufacture through non-contact, automated processing.
3Manufacturing precision
If multiple scanning patterns are used to ablate hollow structures, then manufacturing precision and flexibility are improved, but process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the ablation process into multiple scanning patterns (e.g., parallel line scanning, meandering scanning, spiral scanning, contour scanning). Each scanning pattern is optimized for specific portions of the hollow structure formation process. The complex three-dimensional hollow structures are created by segmenting the ablation into multiple passes with different scanning trajectories, allowing precise control over wall thickness, surface quality, and internal geometry while managing process complexity through systematic pattern selection.
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 the precise incorporation of temperature-regulating hollow structures with improved flexibility and process effectiveness, reducing FIVs and enhancing the heat transfer efficiency, thereby maintaining the stability and performance of EUV mirrors in semiconductor technology.
Implementation Method 1
progressively focusing a processing light beam on ablation locations at which temperature-regulating hollow structures are intended to arise, such that the substrate material is modified or ablated at the ablation locations
Implementation Method 2
at the ablation focus the processing light beam inputs energy with an energy density H into the substrate material, which is high enough that the substrate material is modified or ablated
Data Source
AI summary
In a method for incorporating temperature-regulating hollow structures into a substrate, in particular into a substrate for an optical element, such as a mirror for an EUV projection exposure apparatus, there are the following steps: (A) providing a substrate; (B) progressively focusing a processing light beam on ablation locations at which temperature-regulating hollow structures are intended to arise; (C) a scanning process is carried out in which the processing light beam is guided with a focus in such a way that an ablation focus is moved along a scanning trajectory; (D) the scanning trajectory comprises a plurality of scanning patterns; (E) the scanning positions are spaced apart from one another in a longitudinal direction of the temperature-regulating hollow structure to be produced; and (F) the scanning trajectory additionally comprises pattern jump paths.