Pellicle Frame Air Vents for Photolithography Haze Reduction
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Solution Overview
Problem
Current pellicles for photolithography in semiconductor manufacturing suffer from poor ventilation efficiency, leading to the accumulation of gases within the closed space between the pellicle and the mask, which react with ultraviolet light to form haze-like substances such as ammonium sulfate, affecting the quality of the mask substrate during exposure to shorter wavelength light.
Innovation Solution
A pellicle with a frame featuring a plurality of air vents covered by dustproof filters, where the air vents are counterbored with an outwardly diverging counterbore and a tapered wall surface, allowing for effective ventilation and discharge of internal gases, thereby reducing the production of haze on the mask substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air vents are formed in the pellicle frame, then ventilation efficiency is improved, but dustproof protection is worsened
Solution Approach 1:
A dustproof filter is introduced as an intermediary component between the air vent and the external environment. The filter allows air to pass through while blocking dust particles, thus resolving the contradiction between ventilation efficiency and dustproof protection. The filter acts as a mediator that selectively permits gas flow while preventing harmful dust contamination.
Solution Approach 2:
The dustproof filter utilizes porous material structure with controlled pore sizes that allow gas molecules to pass through while blocking larger dust particles. This porous structure enables simultaneous achievement of ventilation function and dustproof protection, resolving the technical contradiction between air flow efficiency and contamination prevention.
2Productivity
If multiple air vents are formed in the pellicle frame, then gas discharge is improved, but structural strength is worsened
Solution Approach 1:
The pellicle frame is segmented into multiple sections with air vents distributed across different locations rather than concentrating openings in one area. This segmentation approach allows gas discharge from multiple points simultaneously improving ventilation efficiency while distributing structural stress across the frame, maintaining overall structural strength.
Solution Approach 2:
The air vents are positioned at different locations and orientations on the frame structure, utilizing spatial distribution in multiple dimensions. This dimensional arrangement optimizes gas discharge pathways while the frame's three-dimensional structure provides structural reinforcement, resolving the contradiction between discharge efficiency and structural integrity.
3Object-affected harmful factors
If the pellicle frame is sealed to prevent dust entry, then dustproof protection is improved, but ventilation is worsened
Solution Approach 1:
The pellicle frame exhibits local quality differentiation: most of the frame structure maintains sealed characteristics for dustproof protection, while specific localized regions contain air vents with filters for ventilation. This local quality approach allows simultaneous achievement of dustproof protection and ventilation efficiency by applying different functional characteristics to different parts of the frame.
Solution Approach 2:
Dustproof filters are positioned at the air vent locations as intermediary components that enable controlled exchange between the sealed internal environment and external atmosphere. The filters act as mediators that permit necessary gas flow while maintaining the sealed dustproof characteristic of the overall frame structure.
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 design effectively introduces and discharges external air, preventing the accumulation of gases and reducing haze formation on the mask substrate, even under exposure to shorter wavelength ultraviolet light, thus enhancing the photolithography process.
Implementation Method 1
each of the vents is covered up with a dustproof filter
Implementation Method 2
a pellicle film that highly transmits exposure light
Implementation Method 3
an adhesion layer is provided that is composed of a polybutene resin, a polyvinyl acetate resin, an acrylic resin, a silicone resin or other resins
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
There is provided a pellicle for photolithography having a plurality of air vents formed in a pellicle frame for photolithography and having the air vents covered with a dustproof filter in which the air vents in the frame are counterbored and a counterbored wall surface of the air vents is tapered.