EUV Optical Element Antireflection Coating Thermal Manipulation
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Solution Overview
Problem
Existing optical elements in projection systems, particularly those used in the EUV and VUV wavelength ranges, face challenges in thermal manipulation due to significant reflection of heating radiation, which can lead to parasitic heating and unwanted deformation, as mechanical manipulators are insufficient for correcting higher-order wavefront errors.
Innovation Solution
An optical element comprising a substrate with a reflective coating and an antireflection coating between the substrate and the reflective coating, designed to suppress the reflection of heating radiation by achieving destructive interference, ensuring that the heating radiation is absorbed rather than transmitted, thereby preventing parasitic heating and allowing for precise thermal manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a reflective coating is used to reflect the exposure beam, then the optical element can be used in EUV/VUV wavelength ranges, but heating radiation is significantly reflected causing parasitic heating and unwanted deformation
Solution Approach 1:
The coating is divided into multiple functional layers: a reflective coating for the exposure beam and a separate antireflection coating for heating radiation. This segmentation allows each layer to be optimized for its specific function without compromising the other.
Solution Approach 2:
The antireflection coating acts as an intermediary layer between the substrate and the reflective coating. It specifically targets heating radiation and converts the harmful reflected heating into absorbed heating, preventing parasitic heating while maintaining the reflective function.
2Manufacturing precision
If mechanical manipulators are used to correct wavefront errors, then low-order aberrations can be corrected, but higher-order wavefront errors caused by thermal load cannot be compensated sufficiently
Solution Approach 1:
The patent replaces mechanical manipulation with thermal manipulation. By controlling the temperature distribution in the optical element through targeted heating, the optical properties are changed to correct higher-order wavefront errors that mechanical manipulators cannot address.
Solution Approach 2:
The patent changes the physical state parameter (temperature) of the optical element to correct wavefront errors. By controlling temperature distribution, the refractive index or reflective properties are modified to compensate for higher-order aberrations.
3Ease of operation
If heating radiation is radiated onto the optical element for thermal manipulation, then wavefront errors can be corrected, but significant reflection of heating radiation causes parasitic heating
Solution Approach 1:
The antireflection coating converts the harmful reflected heating radiation into beneficial absorbed heating. By designing the coating to absorb heating radiation, the system turns what would be parasitic heating into useful thermal energy for correcting wavefront errors.
Solution Approach 2:
The patent uses wavelength-selective properties of the coating, effectively changing the 'optical color' or absorption characteristics for different wavelengths. The coating is designed to reflect the exposure beam wavelength while absorbing the heating radiation wavelength.
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 effectively suppresses the reflection of heating radiation, preventing parasitic heating and enabling targeted, spatially resolved thermal manipulation of optical elements, thereby improving the correction of wavefront errors and maintaining the optical element's accuracy and performance.
Implementation Method 1
an antireflection coating arranged between the substrate and the reflective coating for suppressing the reflection of heating radiation by achieving destructive interference
Implementation Method 2
ensuring that the heating radiation is absorbed rather than transmitted
Data Source
AI summary
An optical arrangement includes an optical element (1) and a thermal manipulation device. The optical element has a substrate (2), a coating (3, 9, 5) applied to the substrate (2), and an antireflection coating (3). The coating (3, 9, 5) includes: a reflective multi-layer coating (5b) configured to reflect radiation (4) with a used wavelength (λEUV). The antireflection coating (3) is arranged between the substrate (2) and the reflective multi-layer coating (5b) to suppress reflection of heating radiation (7) with a heating wavelength (λH) that differs from the used wavelength (λEUV). The thermal manipulation device has at least one heating light source (8) to produce heating radiation (7).