EUV Mirror Substrate with Inhomogeneous Zero-Crossing Temperature
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Solution Overview
Problem
EUV mirror substrates in lithography face thermal deformation issues due to extreme ultraviolet radiation, leading to imaging quality deterioration, as they exhibit location-dependent operating temperatures and thermal expansion, which existing technologies fail to adequately address.
Innovation Solution
A substrate with a non-statistical, inhomogeneous zero-crossing temperature distribution, featuring a minimum and maximum temperature, is developed, composed of doped quartz glass with titanium dioxide, and produced using specific doping and layering techniques to match the expected operating temperature profile, thereby minimizing thermal expansion and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate uses a uniform zero-crossing temperature distribution, then the manufacturing process is simple, but thermal deformation occurs under EUV radiation leading to image quality deterioration
Solution Approach 1:
The patent applies local quality by creating an inhomogeneous zero-crossing temperature distribution within the substrate, where different regions have different zero-crossing temperatures tailored to compensate for location-dependent thermal expansion under EUV radiation. This allows the substrate to maintain dimensional stability across its surface despite non-uniform heating, thereby improving image quality without requiring overly complex external control systems.
Solution Approach 2:
The patent changes the physical parameter of zero-crossing temperature from a uniform distribution to a specifically designed inhomogeneous distribution. By adjusting the zero-crossing temperature parameter locally within the substrate material, the invention enables compensation for thermal deformation patterns, resolving the contradiction between manufacturing simplicity and imaging precision.
2Reliability
If the substrate material is doped with titanium dioxide to adjust zero-crossing temperature, then thermal expansion control is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent implements local quality by varying the titanium dioxide doping concentration spatially within the substrate to create regions with different zero-crossing temperatures. This local variation in dopant concentration allows precise control of thermal expansion characteristics in different areas, improving reliability while the doping process itself remains integrated into the existing glass manufacturing workflow.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the titanium dioxide content to modify the zero-crossing temperature of the glass substrate. This chemical composition adjustment provides a reliable method for controlling thermal expansion behavior, and when combined with established doping techniques, the manufacturing complexity increase is manageable.
3Manufacturing precision
If the zero-crossing temperature distribution is adjusted to match operating temperature profile, then thermal deformation is minimized, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the zero-crossing temperature distribution within the substrate during manufacturing to match the anticipated operating temperature profile. This proactive approach minimizes thermal deformation before the substrate is put into service, and by establishing the temperature distribution in advance, it reduces the need for high-precision real-time measurements and adjustments during operation.
Solution Approach 2:
The patent employs parameter changes by modifying the zero-crossing temperature distribution to correspond with the expected operating conditions. This pre-configured parameter adjustment enables the substrate to inherently compensate for thermal effects, reducing manufacturing precision requirements for subsequent assembly and operation while maintaining excellent thermal deformation control.
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 substrate achieves minimal thermal deformation and maintains high imaging quality by adapting the zero-crossing temperature distribution to the temperature profile induced by EUV radiation, ensuring precise processing of microelectronic components and integrated circuits.
Implementation Method 1
The substrate typically consists of a zero-expansion material and has location-independent zero-crossing temperatures for thermal expansion. When irradiated with extreme ultraviolet radiation in an EUV projection system, the EUV mirror exhibits location-dependent operating temperatures.
Implementation Method 2
The radiation penetrating the mirror substrate causes thermal volume changes, which can lead to surface deformations. Even minute volume changes on the order of 1 nm can result in noticeable degradation and distortion of the image quality.
Implementation Method 3
The zero-crossing temperature in glasses can be adjusted by doping with TiO2. DE 10 2010 009 589 B4 describes a process for producing a blank made of titanium-doped, high-silica glass for a mirror substrate for use in EUV lithography.
Data Source
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AI summary
The present invention relates to a substrate for an EUV mirror which has a zero crossing temperature profile that is different from the statistical distribution. The invention further relates to a method for producing a substrate for an EUV mirror and to the use thereof, the zero crossing temperature profile in the substrate being adapted to the operating temperature of the mirror. The invention also relates to a lithography method using said substrate.