Pellicle Ventilation Hole Chamfering for Dust Reduction
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Solution Overview
Problem
In the manufacturing of semiconductor devices and liquid crystal displays, dust on photomasks causes pattern deformation and quality issues due to light absorption or refraction, and existing pellicle designs struggle with effective cleaning and dust prevention, especially in large-sized pellicles where ventilation holes are difficult to clean and prone to dust generation.
Innovation Solution
A pellicle design featuring a rectangular frame with chamfered and tapered ventilation holes, a filter covering the external opening, and a smooth inner surface roughness of Ra1 μm or less to prevent dust generation and facilitate cleaning, combined with a pressure-sensitive adhesive to secure the filter and prevent foreign substance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple filters are installed to ensure ventilation amount in large-sized pellicles, then foreign substance trapping performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention changes the physical parameters of the ventilation hole by applying chamfering (C0.5 to C1.0) and rounding (R0.5 to R1.0) to the peripheral edge portion. This geometric parameter modification enables a single filter to achieve the ventilation performance that previously required multiple filters, while maintaining effective foreign substance trapping.
2Ease of manufacture
If ultrasonic washing is applied to clean the pellicle frame, then washing effectiveness is improved, but the inside of the ventilation hole remains difficult to clean due to limited ultrasonic wave penetration
Solution Approach 1:
The invention applies rounding (R0.5 to R1.0) to the peripheral edge portion of the ventilation hole, creating a curved transition instead of a sharp corner. This curvature allows ultrasonic waves to penetrate more effectively into the ventilation hole during washing, significantly improving the cleanability of this previously difficult-to-reach area.
3Reliability
If a filter is installed to prevent foreign substance entrance, then foreign substance trapping is improved, but dust generation occurs from the peripheral edge portion of the ventilation hole
Solution Approach 1:
The invention modifies the geometric parameters of the ventilation hole peripheral edge by applying chamfering (C0.5 to C1.0) and rounding (R0.5 to R1.0). This parameter change eliminates sharp edges that generate dust, while the chamfered surface provides a smooth transition that prevents filter contact with the hole edge, thereby preventing dust generation while maintaining foreign substance trapping performance.
4Productivity
If the ventilation hole is made larger to improve ventilation performance, then air flow is improved, but the hole becomes longer and washing performance decreases
Solution Approach 1:
The invention applies rounding (R0.5 to R1.0) to the peripheral edge of the ventilation hole, creating a curved profile that improves ultrasonic wave penetration during washing. This curvature allows effective cleaning even when the ventilation hole is made larger and longer, thereby maintaining washing performance despite increased ventilation requirements.
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 significantly reduces dust generation from the ventilation hole, enhances cleaning effectiveness, and allows for accurate foreign substance inspection, resulting in a reliable pellicle that prevents foreign substance adhesion and ensures high washing performance.
Implementation Method 1
the pellicle frame is washed by means such as ultrasonic washing or the like in surfactant or purified water
Implementation Method 2
a pressure-sensitive adhesive layer made of polybutene resin, polyvinyl acetate resin, acrylic resin and the like for attaching to a photomask
Data Source
AI summary
There is provided a pellicle which has a ventilation hole made through at least one frame bar for adjusting the pressure inside the frame to the atmospheric pressure, and a filter to cover up the external opening of the ventilation hole for preventing entrance of a foreign substance, and at least one of two openings of the ventilation hole is chamfered to a degree selected from a group consisting of “C0.5 to C1.0” and “R0.5 to R1.0”.