Carbon-Based Optical Filter for EUV Lithography OoB Wavelength Removal
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Solution Overview
Problem
Extreme ultraviolet lithography (EUV) processes face errors in photoresist patterns due to out-of-band (OoB) wavelengths in EUV light, which are not effectively filtered by existing methods, leading to contamination and pattern deformation.
Innovation Solution
Incorporating a carbon-based optical filter and dynamic gas lock membrane in the EUV lithography apparatus to filter out OoB wavelengths from the EUV light, while maintaining high transmittance for the desired EUV wavelengths and preventing gas diffusion from the photoresist film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pellicle is used to prevent contamination of the EUV mask, then mask protection is improved, but the pellicle reflects OoB wavelength light causing pattern errors
Solution Approach 1:
A carbon-based optical filter is introduced as an intermediary component between the light source and the EUV mask. This filter selectively absorbs OoB wavelength light while transmitting the desired EUV wavelengths, thereby preventing pattern errors without compromising mask protection. The filter acts as a mediator that resolves the conflict between maintaining mask protection and ensuring pattern accuracy.
Solution Approach 2:
The patent changes the optical parameters of the light path by introducing a carbon-based filter with specific spectral transmission characteristics. This filter is designed to transmit EUV wavelengths (13.5 nm) while absorbing OoB wavelengths, thereby modifying the wavelength composition of the light reaching the mask and photoresist, and eliminating pattern errors caused by OoB light reflection from the pellicle.
2Manufacturing precision
If the peripheral reflecting region of the EUV mask is reduced to remove OoB light, then pattern accuracy is improved, but mask effectiveness is reduced
Solution Approach 1:
Instead of modifying the mask structure, a carbon-based optical filter is placed in the light path as an intermediary to selectively remove OoB wavelength light before it reaches the mask. This approach maintains the full effectiveness of the mask while achieving pattern accuracy by filtering out harmful wavelengths upstream.
Solution Approach 2:
The harmful OoB wavelength light is extracted from the EUV light beam using a carbon-based optical filter. This extraction occurs in the light path before the light reaches the mask, allowing the mask to maintain its full reflecting effectiveness while the unwanted wavelengths are removed, thus achieving both pattern accuracy and mask effectiveness.
3Manufacturing precision
If a carbon-based optical filter is added to filter OoB wavelengths, then pattern accuracy is improved, but device complexity increases
Solution Approach 1:
The patent utilizes the inherent optical properties of carbon-based materials, which naturally exhibit high absorption for OoB wavelengths and high transmission for EUV wavelengths. By selecting a material with appropriate spectral characteristics, the filter achieves wavelength-selective filtering without requiring complex multi-layer structures or additional optical components, thus minimizing the increase in device complexity.
Solution Approach 2:
The optical filter is made from carbon-based materials (such as carbon nanotubes, graphene, or amorphous carbon) that possess unique optical properties for EUV wavelengths. These composite materials provide both the required filtering function and structural integrity, achieving effective OoB light removal with a relatively simple single-material filter structure rather than complex multi-material assemblies.
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 significantly reduces errors in photoresist patterns by effectively filtering OoB wavelengths and blocking gas diffusion, ensuring accurate pattern formation and minimizing contamination in the EUV lithography process.
Implementation Method 1
The carbon-based optical filter may filter a light having an OoB wavelength from the EUV light
Implementation Method 2
The carbon-based DGL membrane may be installed at the DGL to block a diffusion of a gas released from the photoresist film caused by the EUV light
Data Source
AI summary
An EUV lithography apparatus may include a light source, an EUV mask and a carbon-based optical filter. The light source may generate an EUV light. The EUV mask may be configured to apply the EUV light to a photoresist film on a substrate. The carbon-based optical filter may filter a light having an OoB wavelength in the EUV light. Thus, the EUV light may not include the light having the OoB wavelength to decrease an error of a photoresist pattern formed using the EUV light.