Photomask Pellicle Frame Assembly with Magnetic Bonding and Venting
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Solution Overview
Problem
Conventional pellicle mounting on photomasks requires precise alignment, complicates frame detachment, necessitates ventilation holes, and adhesive can act as particles, leading to potential damage and decreased exposure accuracy in EUV lithography processes.
Innovation Solution
A frame assembly using magnetic bonding between a stud and fixture, eliminating the need for precise alignment and ventilation holes, and containing adhesive within a recess to minimize particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied between the frame and photomask for bonding, then the frame can be securely mounted on the photomask, but the adhesive may act as particles during EUV exposure, leading to decreased exposure accuracy
Solution Approach 1:
The adhesive is extracted from the exposure environment by placing it in a recessed cavity within the frame structure. This removes the harmful adhesive particles from the path of EUV exposure light while maintaining the bonding function between the frame and photomask.
Solution Approach 2:
The recessed cavity structure acts as an intermediary that contains the adhesive in a protected location. This intermediate structure allows the adhesive to perform its bonding function without directly exposing particles to the EUV light path.
2Reliability
If ventilation holes are formed in the frame to buffer pressure changes, then the membrane can accommodate vacuum conditions, but the high-precision machining process increases manufacturing costs
Solution Approach 1:
The ventilation function is merged with the existing frame structure by utilizing the recessed cavity and stud-fixture assembly. The gap created by the stud and fixture serves as the ventilation pathway, eliminating the need for separate precision-machined ventilation holes.
Solution Approach 2:
The ventilation function is extracted from the frame body and relocated to the gap between the stud and fixture components. This simplifies the frame manufacturing process while maintaining pressure buffering capability.
3Manufacturing precision
If precise positioning alignment is required to mount the frame at the exact location on the photomask, then accurate patterning is achieved, but the mounting process becomes complex and time-consuming
Solution Approach 1:
The magnetic bonding mechanism provides self-alignment during the mounting process. The magnetic attraction between the stud and fixture automatically draws the components together into proper alignment, eliminating the need for complex precision positioning procedures.
Solution Approach 2:
The mechanical precision alignment process is replaced with a magnetic field-based alignment system. The magnetic attraction force between the stud and fixture automatically positions the components accurately without requiring complex mechanical positioning equipment or procedures.
4Ease of repair
If the frame is detached from the photomask for pellicle replacement, then the pellicle can be replaced, but the separation process is complicated and carries risk of damage
Solution Approach 1:
The mechanical adhesive bonding is replaced with a magnetic bonding system that allows for easy separation. The magnetic attraction can be quickly overcome by simple mechanical actions, enabling straightforward pellicle replacement without complex separation tools or procedures.
Solution Approach 2:
The frame assembly is segmented into separable magnetic components (stud and fixture) that can be easily detached from the photomask. This modular magnetic connection allows for simple separation and reassembly operations, facilitating convenient pellicle 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
Facilitates easy frame separation, reduces manufacturing costs, and enhances exposure accuracy by preventing adhesive exposure and out-gassing, suitable for EUV photolithography processes.
Implementation Method 1
The stud and the fixture are magnetically bonded to each other
Data Source
AI summary
A frame assembly for mounting a pellicle on a photomask is disclosed. The frame assembly includes a frame to which the pellicle is attached, a stud attached to the photomask, and a fixture that is inserted into the lower side of the frame. The stud and the fixture are magnetically bonded to each other, and a gap of a certain height is created between the photomask and the frame by the stud under the fixture. This eliminates the need for precise alignment of the frame during the mounting process on the photomask, and facilitates the separation of the frame from the photomask for reuse. The formation of the gap eliminates the need for a separate process to create vent holes in the frame.