Carbon-Based EUV Mask Pellicle Membrane Fabrication
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Solution Overview
Problem
Conventional pellicle fabrication techniques for EUV masks are inadequate due to the difficulty in producing thin, highly transmissive membranes with sufficient structural integrity, often resulting in distortion, wrinkling, breaking, or shattering, which leads to particle contamination in the processing chamber.
Innovation Solution
The use of carbon-based pellicle membranes, such as graphene, graphene-silicon carbide (SiC), and SiC membranes, which offer superior mechanical and thermal properties, including high thermal conductivity and emissivity, to provide a stronger and more reliable pellicle that mitigates the risk of shattering and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional fabrication processes are used to produce thin pellicle membranes, then the pellicle can be made thin and transmissive, but the pellicle becomes distorted, wrinkled, broken, or damaged
Solution Approach 1:
The patent employs composite material structures for the pellicle, combining multiple layers with different properties. This includes using supported membranes where a thin film is supported by a substrate structure, and combining materials with complementary characteristics to achieve both thinness and mechanical strength. The composite approach allows the pellicle to maintain structural integrity while remaining thin enough for EUV transmission.
Solution Approach 2:
The patent utilizes thin film structures that are specifically designed to maintain flexibility and structural integrity at minimal thickness. This includes using supported membrane configurations where the thin film is backed by a supportive substrate, allowing the pellicle to be extremely thin while preventing distortion and breaking during fabrication and operation.
2Ease of manufacture
If conventional fabrication processes are used, then manufacturing is simpler, but the pellicle may shatter and cause particle contamination
Solution Approach 1:
The composite structure provides inherent shatter resistance by distributing mechanical stress across multiple layers. The supported membrane configuration ensures that even if the thin film were to fail, the supporting substrate prevents complete shattering, thereby eliminating particle contamination sources while maintaining manufacturing feasibility.
Solution Approach 2:
The supporting substrate acts as a cushioning element that prevents the thin pellicle membrane from shattering during fabrication and operation. This beforehand protective measure ensures that even under stress, the membrane cannot break into particles, thereby preventing contamination of the processing chamber.
3Use of energy by moving object
If thin high-transmission material is used for the pellicle, then EUV transmission is maintained, but the pellicle becomes more vulnerable to damage
Solution Approach 1:
The patent uses thin film structures that are specifically engineered to maximize EUV transmission while maintaining sufficient mechanical strength through the supported membrane configuration. The thin film allows high EUV transmission, while the supporting substrate provides the necessary mechanical strength to prevent damage during handling and operation.
Solution Approach 2:
The composite structure combines materials with complementary properties: the thin film layer provides high EUV transmission, while the supporting substrate provides mechanical strength. This composite approach resolves the contradiction by assigning different functions to different layers of the composite structure.
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 carbon-based pellicle membranes provide enhanced mechanical strength and thermal management, ensuring lower temperatures during EUV exposure, thus preventing shattering and extending pellicle lifetime, while maintaining high EUV transmission and reducing process chamber contamination.
Implementation Method 1
which offer superior mechanical and thermal properties, including high thermal conductivity and emissivity
Implementation Method 2
which offer superior mechanical and thermal properties, including high thermal conductivity and emissivity
Data Source
AI summary
A method for fabricating a pellicle includes forming a first dielectric layer over a back surface of a substrate. After forming the first dielectric layer, and in some embodiments, a graphene layer is formed over a front surface of the substrate. In some examples, after forming the graphene layer, the first dielectric layer is patterned to form an opening in the first dielectric layer that exposes a portion of the back surface of the substrate. Thereafter, while using the patterned first dielectric layer as a mask, an etching process may be performed to the back surface of the substrate to form a pellicle having a pellicle membrane that includes the graphene layer.