Pellicle Frame Protrusion Design for Photomask Flatness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pellicle frames cause deformation to photomasks during adhesion due to their rigidity and shape, leading to quality issues in semiconductor and display panel manufacturing, and existing solutions either compromise on frame rigidity or result in insufficient stand-off distance, making handling and adhesion challenging.
Innovation Solution
A pellicle frame design featuring vertically and horizontally protruding parts with specific thickness and flatness, integrated with a mask-bonding agglutinant layer, allows for flexible adhesion with reduced load, minimizing photomask deformation while maintaining frame rigidity and sufficient stand-off distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pellicle frame is made rigid to maintain frame shape during manufacturing and handling, then the frame rigidity is improved, but the photomask deformation increases due to the frame's shape affecting the photomask when adhered together
Solution Approach 1:
The pellicle frame is divided into a main body portion and a protruding portion. The protruding portion extends from the lower annular face and has a different cross-sectional shape (smaller area) than the main body, allowing the frame to be segmented into functional zones: the main body maintains rigidity while the protruding portion reduces contact area and deformation transfer to the photomask.
Solution Approach 2:
Different portions of the frame are given different structural properties. The main body has sufficient rigidity for handling, while the protruding portion has reduced cross-sectional area (thickness of 0.3-1mm) to minimize its effect on photomask deformation. The agglutinant layer is also applied locally on the protruding portion's lower face, concentrating the bonding function in a specific area.
2Manufacturing precision
If the pellicle frame rigidity is reduced to minimize photomask deformation, then the photomask flatness is improved, but the handling and manufacturing become difficult due to excessive flexibility
Solution Approach 1:
The frame structure is segmented into a rigid main body for handling and a flexible protruding portion for photomask bonding. This segmentation allows the frame to maintain overall rigidity for easy handling while the protruding portion can flexibly adapt to the photomask surface, reducing deformation.
Solution Approach 2:
The frame employs a composite structural design combining rigid main body material with a thinner, more flexible protruding portion. This composite approach allows simultaneous achievement of handling rigidity and photomask-friendly flexibility in different parts of the same component.
3Manufacturing precision
If the height of the pellicle frame is reduced to improve flatness copying ability, then the photomask deformation is reduced, but the stand-off distance becomes insufficient reducing the defocusing effect
Solution Approach 1:
Instead of reducing the overall frame height (vertical dimension), the invention extends the frame horizontally by adding a protruding portion that contacts the photomask. This dimensional shift allows the bonding interface to be moved to a different spatial location, maintaining stand-off distance while enabling better flatness copying through the protruding portion's flexibility.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A pellicle is proposed in which the frame is formed with an external horizontal slit for the purpose of receiving a pressing means, which can urge the pellicle to be adhered to a photomask, in which the slit forms a vertically protruding part of a thickness of 5 - 30 % of the width of a pellicle frame main body and a horizontally protruding part of a thickness of 0.3 - 1mm; also the method of adhering the pellicle to the photomask is proposed.