EUV Pellicle Support Frame Ventilation Design
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, the attachment of a pellicle to a photomask is essential for preventing contamination, but the limited space in EUV exposure devices requires a redesigned pellicle with a height of half or less than conventional pellicles, and the vacuum environment poses challenges with pressure differentials causing the pellicle film to sag or bulge, necessitating a vent hole with a filter that must prevent foreign matter entry while maintaining adequate ventilation.
Innovation Solution
A support frame with a through hole extending in a first direction and a second direction, featuring a filter arranged inside or at the end of the through hole, is designed to facilitate easier evacuation, reduce filter degradation, and allow for a three-dimensional vent hole configuration using stacked frame-shaped plates, ensuring efficient ventilation and particle capture within the limited space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a conventional pellicle with height of 5 mm or more is used, then adequate ventilation space is available, but the installation space in EUV exposure device is insufficient
Solution Approach 1:
The vent hole is configured to extend in the thickness direction of the frame body, utilizing the third dimension (depth) rather than only horizontal expansion. This allows adequate ventilation volume to be achieved within the constrained horizontal installation space by creating a through-hole that penetrates the frame body thickness, effectively solving the space conflict between pellicle height and installation area.
2Reliability
If a filter is added to prevent foreign matter entry, then contamination protection is improved, but the vent hole ventilation efficiency is reduced
Solution Approach 1:
A filter is installed at one end of the vent hole to block foreign matter while allowing gas molecules to pass through. The filter's porous structure enables adequate ventilation efficiency to be maintained while providing contamination protection, resolving the contradiction between reliability and productivity.
3Illumination intensity
If the pellicle film is made thinner for EUV light transmission, then light transmission is improved, but the film becomes more susceptible to sagging and bulging under vacuum
Solution Approach 1:
The pellicle film is designed as an ultrathin film (30-100 nm) that is stretched and fixed on the frame body, utilizing tension to maintain flatness. The thin film structure optimizes EUV light transmission while the mechanical configuration (stretched and fixed) compensates for the susceptibility to sagging under vacuum conditions.
Solution Approach 2:
The frame body provides structural support that counteracts the vacuum pressure differential acting on the pellicle film. By positioning the vent hole through the frame body thickness and providing rigid support structures, the system balances the vacuum forces to prevent film deformation.
4Ease of manufacture
If multiple frame-shaped plates are stacked to create three-dimensional vent hole, then manufacturing flexibility is improved, but the device complexity increases
Solution Approach 1:
The frame body is divided into multiple frame-shaped plates stacked in the thickness direction, with vent holes formed by aligning openings across the plates. This segmentation allows flexible configuration of the vent hole path while maintaining manufacturing simplicity through standardized plate components.
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 solution enables faster evacuation, suppresses filter degradation, and allows for the arrangement of a pellicle film with a high-performance filter that captures 99.7% of particles, ensuring effective protection against contamination and maintaining the integrity of the EUV exposure process.
Implementation Method 1
a filter arranged at an inside of the through hole or at an end of the through hole
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
Provided is a supporting frame in which a vent hole detachably arranging a filter and to which a pellicle film for extreme ultraviolet lithography can be attached. A support frame according to an embodiment of the present invention is a support frame for arranging a pellicle film, the support frame has a through hole being made from a hole extending along a first direction, the first direction being almost parallel to a surface direction of the pellicle film, and a hole extending along a second direction, the second direction not being parallel to the first direction; and the support frame includes a filter, the filter arranged at an inside of the through hole or at an end of the through hole, and the filter is arranged apart from the pellicle film.