EUVL Precision Component Near-Zero Thermal Expansion
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Solution Overview
Problem
Current precision EUVL components, particularly glass-ceramics, face challenges with thermal hysteresis and coefficient of thermal expansion (CTE) homogeneity, leading to imaging errors and inaccuracies in EUV lithography, especially at temperatures around room temperature.
Innovation Solution
A precision EUVL component with an average CTE of at most 0±0.1×10−6/K and thermal hysteresis of <0.1 ppm in the temperature range from 19 to 25°C, utilizing an LAS glass-ceramic composition with optimized SiO2, Li2O, and nucleating agents like TiO2, ZrO2, and WO3, which minimizes thermal hysteresis and ensures zero expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reflective multilayer stack systems are used in EUV lithography, then imaging capability is improved, but thermal load on the photomask substrate increases due to absorbed radiation
Solution Approach 1:
The patent changes the thermal expansion parameter of the substrate material by selecting specific glass-ceramic compositions (e.g., LAS glass-ceramic with controlled crystal phases) that exhibit near-zero thermal expansion. This allows the substrate to maintain dimensional stability despite thermal loading from EUV radiation absorption, resolving the contradiction between imaging capability and thermal management
Solution Approach 2:
The patent employs composite glass-ceramic materials combining amorphous glass matrices with crystalline phases (such as beta-spodumene, diopside, or periclase). This composite structure provides both mechanical strength and exceptional thermal expansion control, enabling the substrate to withstand thermal loads while maintaining imaging precision
2Temperature
If active cooling concepts are implemented for the photomask, then thermal management is improved, but thermal hysteresis effects increase leading to imaging errors
Solution Approach 1:
The patent modifies the thermal hysteresis parameter by selecting glass-ceramic compositions with specific crystalline phase transformations that occur at temperatures outside the operating range. This minimizes thermal hysteresis effects during actual lithography operations, allowing active cooling to effectively manage thermal loads without introducing significant imaging errors
3Stability of the object's composition
If materials with low thermal expansion are used for the photomask substrate, then thermal deformation is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent changes the material composition parameters to achieve near-zero thermal expansion through carefully controlled glass-ceramic formulations. By optimizing the ratio of glass phases to crystalline phases and selecting appropriate nucleating agents, the patent achieves dimensional stability while maintaining compatibility with existing ceramic manufacturing processes
Solution Approach 2:
The patent incorporates preliminary heat treatment and controlled crystallization steps during manufacturing to establish the desired microstructure before final processing. This preliminary action ensures that the substrate achieves its target thermal expansion properties early in the manufacturing process, simplifying subsequent fabrication steps
4Productivity
If higher EUV beam power is used to increase throughput, then productivity is improved, but thermal load on the photomask and carrier increases
Solution Approach 1:
The patent changes the thermal properties of the substrate and carrier materials by selecting glass-ceramic compositions with tailored thermal expansion coefficients and heat capacity. This enables the system to handle higher EUV beam powers and increased throughput while maintaining thermal stability and preventing deformation that would compromise imaging quality
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
The solution provides improved thermal characteristics, reduced thermal hysteresis, and enhanced CTE homogeneity, resulting in precise EUVL components with minimal imaging errors and increased accuracy in EUV lithography applications.
Implementation Method 1
a precision EUVL component having an average coefficient of thermal expansion CTE in the range from 0 to 50° C. of at most 0±0.1×10−6/K
Implementation Method 2
a thermal hysteresis of <0.1 ppm in the temperature range from 19 to 25°C
Data Source
AI summary
A precision extreme ultraviolet lithography (EUVL) component having an average coefficient of thermal expansion (CTE) in a range from 0 to 50° C. of at most 0±0.1×10−6/K, and a thermal hysteresis of <0.1 ppm at least in the temperature range from 19 to 25° C., and an index F of <1.2. F=TCL (0; 50° C.)/|expansion (0; 50° C)|, where TCL is a total change of length.