Pellicle Film Demounting With Adhesive Capture for Clean Photomasks
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Solution Overview
Problem
Conventional pellicle demounting methods risk contaminating photomasks due to scattering of pellicle film pieces during demounting, which is exacerbated by the use of EUV lithography where contaminants can absorb and scatter EUV light, affecting exposure accuracy.
Innovation Solution
A pellicle demounting method involving the formation of a pressure-sensitive adhesive layer on the pellicle film before demounting, using methods like spray coating, to trap pellicle film pieces and reduce contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pellicle is mounted on a photomask to protect it during EUV lithography, then the photomask is protected from contamination, but the pellicle itself becomes susceptible to contamination and deterioration requiring demounting
Solution Approach 1:
A pressure-sensitive adhesive layer is formed on the pellicle film before demounting operations. This preliminary preparation ensures that when the pellicle is removed, any contaminated or deteriorated pellicle film pieces are captured by the adhesive layer, preventing them from scattering and contaminating the photomask during the demounting process.
2Ease of operation
If conventional demounting methods are used where the pellicle film contacts a sheet directly, then demounting can be performed, but pellicle film pieces scatter and contaminate the photomask
Solution Approach 1:
The pressure-sensitive adhesive layer serves as an intermediary between the pellicle film and the collection surface. Instead of the pellicle film contacting a bare sheet directly, the adhesive layer intermediate captures and holds the pellicle film pieces, preventing their scattering while maintaining ease of demounting operation.
3Reliability
If the pellicle is kept mounted continuously to maintain protection, then photomask protection is continuous, but contaminated or deteriorated pellicles can cause exposure errors
Solution Approach 1:
The pressure-sensitive adhesive layer is prepared in advance on the pellicle film, enabling safe demounting when contamination or deterioration is detected. This allows the pellicle to be removed and replaced without risking photomask contamination, thus maintaining exposure accuracy while preserving the ability to provide continuous protection through timely replacement.
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 method effectively reduces photomask contamination by adhering pellicle film pieces to the adhesive layer, minimizing scattering and maintaining exposure accuracy in EUV lithography.
Implementation Method 1
a step of forming a pressure-sensitive adhesive layer on the pellicle film in the stack; and a demounting step of demounting at least the pellicle film and the pressure-sensitive adhesive layer from the photomask
Data Source
AI summary
A pellicle demounting method includes providing a stack including a photomask, a pellicle frame, and a pellicle film that are arranged in this order, forming of a pressure-sensitive adhesive layer on the pellicle film in the stack, and a demounting step of demounting at least the pellicle film and the pressure-sensitive adhesive layer from the photomask in the stack having the pressure-sensitive adhesive layer formed thereon.