EUV Pellicle Microstructure Mounting for Clean Mask Release
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Solution Overview
Problem
Existing EUV lithography systems face challenges in efficiently mounting and demounting pellicles on EUV photo masks without causing damage or residue, while maintaining vacuum integrity and ensuring high transparency and durability.
Innovation Solution
The use of microstructured adhesive systems, including micro fibers, cones, and magnetic elastomers, to attach pellicles to EUV photo masks, utilizing controlled pressing and heating mechanisms to minimize force and facilitate easy mounting and demounting, while maintaining vacuum conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesive systems are used to attach pellicles to EUV photo masks, then the pellicle can be securely mounted, but the mounting and demounting processes cause damage and leave residue on the photo mask
Solution Approach 1:
The adhesive system is segmented into discrete microstructures (micro fibers, micro cones, or magnetic microstructures) distributed across the frame bottom surface. Each microstructure acts as an independent attachment point, allowing the pellicle to be securely mounted while enabling clean release during demounting without causing damage or residue
Solution Approach 2:
The adhesive properties are changed by using materials with specific characteristics: elastomeric materials with controlled durometer (40-70 Shore A) that provide sufficient bonding strength yet allow easy release, or magnetic materials with controlled strength. The microstructure geometry (fiber diameter 1-50 μm, cone dimensions) is optimized to achieve the right balance between attachment strength and clean demounting
2Stability of the object's composition
If strong adhesive forces are used to secure the pellicle, then the pellicle remains stable during lithography, but the demounting process requires excessive force that may damage the photo mask
Solution Approach 1:
The adhesive force is segmented into many small microstructures rather than one large adhesive area. This distribution allows the pellicle to be stable during use while requiring minimal force per microstructure for release, enabling easy demounting without damage
Solution Approach 2:
The adhesive parameter is changed from permanent strong adhesion to reversible adhesion using elastomeric materials or magnetic forces. These materials provide sufficient holding strength during lithography but allow controlled release with minimal force during demounting
3Ease of manufacture
If traditional mounting methods are used, then the pellicle can be attached, but the process takes excessive time and may compromise vacuum integrity
Solution Approach 1:
The microstructures are pre-formed on the frame bottom surface before pellicle attachment. This preliminary preparation allows rapid pellicle mounting by simply pressing the pellicle onto the pre-positioned microstructures, significantly reducing mounting time while maintaining vacuum integrity
Solution Approach 2:
Traditional mechanical adhesive systems are replaced with elastomeric or magnetic microstructures that enable rapid attachment and release. This substitution simplifies the mounting process and reduces the time required for both mounting and demounting operations
4Illumination intensity
If the pellicle is mounted close to the photo mask surface, then transparency is maximized, but the risk of damage during mounting and demounting increases
Solution Approach 1:
The pellicle is implemented as a thin, flexible membrane that can be mounted close to the photo mask surface to maximize EUV transparency. The flexible nature allows it to conform to the mask surface while the segmented adhesive system ensures gentle attachment that minimizes damage risk
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
Facilitates efficient and residue-free mounting and demounting of pellicles on EUV photo masks, preserving vacuum integrity and reducing operational time, thus enhancing the durability and transparency of the EUV lithography process.
Implementation Method 1
a plurality of micro structures made of an adhesive elastomer... magnetic elastomers
Implementation Method 2
utilizing controlled pressing and heating mechanisms to minimize force and facilitate easy mounting and demounting
Data Source
AI summary
In a method of de-mounting a pellicle from a photo mask, the photo mask with the pellicle is placed on a pellicle holder. The pellicle is attached to the photo mask by a plurality of micro structures. The plurality of micro structures are detached from the photo mask by applying a force or energy to the plurality of micro structures before or without applying a pulling force to separate the pellicle from the photo mask. The pellicle is de-mounted from the photo mask. In one or more of the foregoing and following embodiments, the plurality of micro structures are made of an elastomer.