Pellicle Membrane with 2D Material and Metal Catalyst Support
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Solution Overview
Problem
Current pellicles for photomasks in optical lithography processes face challenges in achieving high optical transmittance, durability, and contamination protection, especially with the reduction in semiconductor device line-widths and the need for shorter wavelengths of light.
Innovation Solution
A pellicle configuration featuring a substrate, a metal catalyst layer, and a two-dimensional (2D) material membrane with a central and edge region structure, where the metal catalyst layer and substrate support the edge region but not the central region, along with a barrier layer and protection film, to enhance durability and optical transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pellicle structure is used, then the photomask is protected from contaminants, but the optical transmittance is insufficient and durability is compromised
Solution Approach 1:
The pellicle membrane is constructed from a two-dimensional material such as graphene, h-BN, or MoS2, which provides both high optical transmittance (>80% in the visible and EUV ranges) and exceptional mechanical strength. This composite approach combines the protective function with high transmittance, resolving the contradiction between durability and optical performance.
Solution Approach 2:
The pellicle is designed as an ultra-thin two-dimensional membrane that maintains structural integrity while minimizing light absorption. The 2D material forms a flexible yet strong barrier that protects the photomask without significantly attenuating the incident light, achieving both protection and high transmittance.
2Illumination intensity
If the pellicle membrane is made thinner to improve transmittance, then optical transmittance increases, but the mechanical strength and durability decrease
Solution Approach 1:
The use of two-dimensional materials like graphene provides a unique solution where the membrane can be extremely thin (single atomic layer) while maintaining exceptional mechanical strength. The 2D structure offers high tensile strength and flexibility, allowing the pellicle to be both thin for high transmittance and strong for durability.
Solution Approach 2:
The invention changes the material parameter from conventional bulk materials to two-dimensional materials, fundamentally altering the strength-to-thickness ratio. This parameter change enables the pellicle to achieve maximum transmittance with minimal thickness while maintaining sufficient mechanical strength through the inherent properties of 2D materials.
3Ease of manufacture
If the pellicle structure is simplified to reduce manufacturing complexity, then manufacturing ease improves, but the ability to protect against contaminants and maintain performance deteriorates
Solution Approach 1:
The invention extracts the protective function into a separate two-dimensional membrane layer that can be independently optimized and manufactured. This allows the pellicle membrane to be produced using specialized 2D material synthesis techniques while the substrate and support structures can be manufactured using conventional photomask fabrication processes, balancing manufacturing ease with protective performance.
Data Source
AI summary
A pellicle configured to protecting a photomask from external contaminants may include a metal catalyst layer and a pellicle membrane including a 2D material on the metal catalyst layer, wherein the metal catalyst layer supports edge regions of the pellicle membrane and does not support a central region of the pellicle membrane. The metal catalyst layer may be on a substrate, such that the substrate and the metal catalyst layer collectively support the edge region of the pellicle membrane and do not support the central region of the pellicle membrane. The pellicle may be formed based on growing the 2D material on the metal catalyst layer and etching an inner region of the metal catalyst layer that supports the central region of the formed pellicle membrane.