Zirconium-SiN3 EUV Radiation Filter for Direct Sensor Detection
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Solution Overview
Problem
Existing radiation sensors for EUV lithographic apparatuses face challenges in accurately measuring EUV radiation due to the presence of conversion layers, optical guides, and adhesives, which reduce accuracy and increase blurring, and are not sufficiently radiation-hard to withstand high doses of EUV radiation over extended periods.
Innovation Solution
A radiation filter comprising zirconium and SiN3 is used to selectively transmit EUV radiation while blocking other wavelengths, integrated with a radiation sensor that includes a passivation layer and a CMOS photodiode, eliminating the need for conversion layers and optical guides, and featuring a protective layer to withstand high EUV doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conversion layer and optical guide are used to enable EUV radiation detection, then the radiation sensor can detect EUV radiation, but the measurement accuracy and resolution are reduced due to blurring and transmission losses
Solution Approach 1:
The patent removes the conversion layer and optical guide from the radiation sensor structure. By directly exposing the photodiode to EUV radiation, the invention eliminates the intermediate components that cause blurring and transmission losses, thereby improving measurement accuracy while maintaining EUV detection capability
Solution Approach 2:
The patent employs a composite filter structure consisting of multiple layers with specific materials (e.g., silicon nitride, silicon oxide, zirconium) and thicknesses. This composite filter selectively transmits EUV radiation while blocking unwanted wavelengths, enabling accurate EUV detection without requiring conversion layers or optical guides
2Reliability
If a conversion layer and optical guide are used for EUV radiation detection, then the sensor can operate at EUV wavelengths, but the device complexity increases due to additional components and adhesives
Solution Approach 1:
The patent extracts and removes the conversion layer, optical guide, and associated adhesives from the sensor structure. This simplification maintains EUV detection functionality while significantly reducing device complexity and the number of components requiring assembly and alignment
Solution Approach 2:
The patent merges the filtering function and detection function into a single integrated structure. The composite filter is directly coupled to the photodiode, eliminating the need for separate conversion layers and optical guides, thereby reducing device complexity while maintaining EUV detection capability
3Device complexity
If known radiation sensors are used without enhanced protection, then the sensor structure is simpler, but the sensor is not sufficiently radiation-hard to withstand high doses of EUV radiation over extended periods
Solution Approach 1:
The patent employs a composite filter structure consisting of multiple layers with specific materials (e.g., silicon nitride, silicon oxide, zirconium) and thicknesses. This composite filter selectively transmits EUV radiation while blocking unwanted wavelengths, enabling accurate EUV detection without requiring conversion layers or optical guides
Solution Approach 2:
The patent optimizes the thickness parameters of each filter layer to achieve the desired balance between EUV transmission and protection against radiation damage. By carefully controlling layer thicknesses, the sensor achieves both radiation hardness and maintained functionality under high EUV doses
4Reliability
If conversion layers and optical guides are used, then EUV radiation can be detected, but the transmission of EUV radiation is reduced leading to lower measurement efficiency
Solution Approach 1:
The patent removes the conversion layer and optical guide from the radiation sensor structure. By directly exposing the photodiode to EUV radiation, the invention eliminates the intermediate components that cause blurring and transmission losses, thereby improving measurement accuracy while maintaining EUV detection capability
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 enhances measurement accuracy, resolution, and efficiency by directly detecting EUV radiation, improving the radiation sensor's stability and longevity under high EUV exposure, reducing maintenance needs and increasing throughput in lithographic processes.
Implementation Method 1
The radiation filter comprising zirconium and SiN3 advantageously transmits incident EUV radiation whilst reducing transmission of other forms of radiation such as DUV radiation, visible radiation and/or infrared radiation
Implementation Method 2
a photodiode arranged to receive radiation transmitted by the passivation layer
Data Source
AI summary
A radiation filter for reducing transmission of an unwanted wavelength of radiation. The radiation filter includes zirconium and SiN3. The radiation filter may form part of a radiation sensor including a passivation layer arranged to receive radiation transmitted by the radiation filter, a photodiode arranged to receive radiation transmitted by the passivation layer, and circuit elements connected to the photodiode. The radiation sensor may perform optical measurements as part of an extreme ultraviolet lithographic apparatus or a lithographic tool.