Detachable EUV Pellicle Frame With Integrated Vent Filter
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, the existing pellicle filters used in photomasks are difficult to replace due to their integration with the pellicle frame, leading to issues with filter degradation and outgassing, which causes contamination and exposure defects in the photomask and optical systems.
Innovation Solution
A support frame design with a detachable filter configuration, where the filter is sandwiched between two frame parts with engaging portions and grooves, allowing for easy attachment and detachment without adhesives, reducing outgassing and facilitating filter replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter is integrated with the pellicle frame by welding, then the filter is securely fixed and provides good heat resistance and ventilation speed, but the filter becomes difficult to replace when degraded by EUV light exposure
Solution Approach 1:
The pellicle frame is divided into multiple parts: a first frame part that holds the filter, and a second frame part that engages with the first frame part. This segmentation allows the filter to be securely fixed during operation while enabling easy removal by separating the frame parts, resolving the contradiction between reliable fixation and ease of replacement.
Solution Approach 2:
The engagement between the first and second frame parts is designed to be dynamic rather than permanent. The engaging portions allow the frame parts to be firmly connected during EUV lithography operations but can be easily separated when filter replacement is needed, transitioning from a static welded connection to a dynamic, reversible connection.
2Reliability
If a vent hole is provided in the pellicle frame for pressure differential relief, then the pellicle film is protected from sagging or swelling, but foreign matter may enter inside the pellicle without adequate filtration
Solution Approach 1:
A filter is installed in the vent hole of the pellicle frame, allowing pressure differential relief while blocking foreign matter. The filter acts as a porous barrier that permits gas flow for pressure equalization but traps dust and other contaminants, resolving the contradiction between maintaining pellicle film integrity and preventing foreign matter contamination.
3Length of stationary object
If the pellicle height is reduced to about half or less of conventional pellicles, then the installation space in the EUV exposure device is sufficient, but the structural complexity of the frame body must be increased to accommodate filters and vent holes
Solution Approach 1:
The frame body is segmented into multiple parts with specialized functions: a first frame part for filter installation, a second frame part for engagement, and integrated vent holes with filters. This segmentation allows each component to be optimized for its specific function while maintaining a compact overall structure that fits within the reduced pellicle height.
Solution Approach 2:
Multiple functions are merged into the compact frame structure: the frame parts provide structural support, contain integrated vent holes for pressure relief, incorporate filters for contamination prevention, and include engaging portions for secure assembly. This merging of functions into a compact design achieves the required functionality within the reduced height constraint.
Data Source
AI summary
A support frame for pellicle is provided including a first support frame part, a second support frame part, and a filter, wherein the filter has a flat plate-shaped frame shape and is sandwiched by the first support frame part and the second support frame part, the first support frame part includes a first body part having a flat plate-shaped frame shape and a first engaging portion protruded from the first body part to a thickness direction of the support frame for pellicle, and the second support frame part includes a second body part having a flat plate-shaped frame shape and a second engaging portion of the second body part engaging with the first engaging portion being arranged in a concave part provided in the thickness direction of the support frame for pellicle.