Compensating Optical Coatings for Stable Microlithography Reflectivity
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Solution Overview
Problem
Optical components in projection exposure apparatuses degrade due to ambient conditions, leading to unwanted changes in wavelength-dependent reflection or transmission curves, impairing the performance of the optical system.
Innovation Solution
Designing optical components with multiple layer systems on different surfaces to have wavelength-dependent reflectivity curves that compensate for each other, maintaining a stable and largely constant reflectivity behavior despite degradation or contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical components are used in projection exposure apparatuses under ambient conditions, then the optical system can perform microlithography functions, but the optical components degrade leading to unwanted changes in wavelength-dependent reflection or transmission curves
Solution Approach 1:
The patent applies parameter changes by deliberately designing layer systems with specific optical properties that will change in response to environmental conditions. The layer systems are engineered to have reflectivity curves that shift with temperature or other ambient parameters, allowing the optical component to maintain stable overall performance despite individual layer degradation.
Solution Approach 2:
The patent uses composite materials by combining multiple layer systems with different optical characteristics on different optical surfaces. Each layer system is made of specific materials with tailored optical properties, and their composite arrangement creates an overall reflectivity behavior that compensates for individual layer degradation, maintaining stable optical performance under ambient conditions.
2Manufacturing precision
If the reflectivity behavior of layer systems changes due to degradation, then the optical component was designed for a specific operating wavelength, but the performance is impaired due to shift of the effective wavelength
Solution Approach 1:
The patent applies preliminary anti-action by pre-designing the layer systems to have opposite wavelength dependencies in their reflectivity curves. This preliminary configuration ensures that when environmental conditions cause wavelength shifts, the layer systems produce compensating effects that counteract each other, maintaining stable overall reflectivity behavior and preventing performance impairment.
Solution Approach 2:
The patent utilizes parameter changes by designing layer systems whose optical parameters are intentionally selected to change with environmental conditions. The layer systems are configured so that their reflectivity curves shift in opposite directions with temperature or other parameter changes, creating a compensating effect that maintains stable overall optical performance despite individual layer variations.
3Reliability
If multiple layer systems are arranged on different optical surfaces with compensating wavelength-dependent reflectivity curves, then stable reflectivity behavior is maintained, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the optical component into multiple independent layer systems located on different optical surfaces. Each layer system is designed and optimized separately with specific compensating reflectivity characteristics, allowing independent control and tuning of optical properties while maintaining overall stable performance through their coordinated arrangement.
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
Ensures stable optical performance by minimizing spectral drift in reflection behavior, even under challenging ambient conditions, by allowing for deliberate structural changes in individual layer systems to counteract environmental effects.
Implementation Method 1
a first layer system (210) which exhibits a first wavelength-dependent reflectivity curve when electromagnetic radiation impinges thereon; and at least one second layer system (220) which exhibits a second wavelength-dependent reflectivity curve when electromagnetic radiation impinges thereon
Data Source
AI summary
An optical component comprises a first layer system exhibiting a first wavelength-dependent reflectivity curve when electromagnetic radiation impinges thereon, and at least one second layer system exhibiting a second wavelength-dependent reflectivity curve when electromagnetic radiation impinges thereon. The first layer system and the second layer system are arranged on different optical surfaces. The wavelength dependencies of the first and the second reflectivity curve at least partially compensate one another so that the relative deviation from a desired reflectivity curve which is linear or constant with respect to the wavelength is no more than 5% within the specified wavelength range for a resultant summated reflectivity for the first layer system and the at least one second layer system. An optical system, such as a microlithography projection exposure apparatus, can include such an optical component.