Anodized Aluminum Pellicle Frame Ion Release
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Solution Overview
Problem
In semiconductor and liquid crystal display panel production, conventional pellicles used as debris shields can release acid and ammonium ions, leading to foreign matter generation during high-resolution lithography, especially with short-wavelength UV light, which affects pattern quality and manufacturing yield.
Innovation Solution
A pellicle with an aluminum frame coated with a 4 to 8 μm thick anodized layer containing a black dye, which reduces ion release and maintains detectability by pellicle detection sensors, is developed. The anodized layer is formed using sulfuric acid or alternative acids, and the black dye helps in minimizing ion detection issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional pellicle frame without anodized layer is used, then the manufacturing process is simpler and cost is lower, but acid and ammonium ions are released during lithography causing foreign matter generation
Solution Approach 1:
An anodized layer is formed on the pellicle frame surface before the lithography process. This preliminary surface treatment creates a protective barrier that prevents ion release during subsequent exposure, eliminating the need for complex ion filtration systems while maintaining manufacturing simplicity
Solution Approach 2:
The pellicle frame combines aluminum base material with an anodized oxide surface layer. This composite structure provides both the mechanical strength of aluminum and the ion-blocking properties of the oxidized surface, resolving the contradiction between simplicity and ion release prevention
2Object-generated harmful factors
If the anodized layer thickness is increased to reduce ion release, then ion blocking performance improves, but detectability by pellicle detection sensor deteriorates
Solution Approach 1:
The anodized layer thickness is precisely controlled within the range of 4-8 μm. This parameter optimization balances two competing requirements: thick enough to block ion release effectively, but thin enough to maintain adequate light transmission for sensor detectability during pellicle positioning
Solution Approach 2:
Instead of applying a thick anodized coating that would completely block detection, a partial thickness (4-8 μm) is applied that provides sufficient ion blocking while leaving enough light transmission for sensor operation. This partial action resolves the contradiction between protection and detectability
3Object-generated harmful factors
If a thick anodized layer is applied to prevent ion release, then foreign matter generation is reduced, but the pellicle frame becomes more complex and costly to manufacture
Solution Approach 1:
The anodized layer is formed as a preliminary surface treatment step before final assembly. This pre-treatment approach integrates ion protection into the manufacturing process itself rather than requiring additional complex components or post-processing steps, maintaining ease of manufacture while preventing foreign matter generation
Solution Approach 2:
The anodized layer is formed through an electrochemical process that uses the aluminum frame itself as the substrate. The frame material serves its own protective function through self-anodization, eliminating the need for separate protective coatings or complex multi-layer structures
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 pellicle effectively reduces the release of acid and ammonium ions, ensuring excellent detectability and preventing foreign matter generation, thereby enhancing the quality and yield of semiconductor and liquid crystal display panel manufacturing.
Implementation Method 1
an aluminum pellicle frame having an anodized layer (hereinafter also called an 'alumite layer') on its entire surface
Implementation Method 2
a transparent pellicle film made of nitrocellulose, cellulose acetate or etc., which allows exposure light to easily pass through
Data Source
AI summary
A pellicle is provided that includes an aluminum pellicle frame having an anodized layer on its entire surface; and a pellicle film stretched over and affixed to an end face of the pellicle frame, the anodized layer having a thickness of 4 to 8 μm.