EUV Pellicle Frame with Structured Ventilation Holes
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, pellicles used in reticle structures face challenges with pressure differences between vacuum and atmospheric environments, leading to potential rupture due to trapped air or dust particles, which affects the integrity and transparency of the pellicle during EUV radiation exposure.
Innovation Solution
A pellicle structure with a frame that includes a plurality of separate, non-connected holes allows for pressure equalization and dust prevention, maintaining a threshold pressure difference by optimizing the number and distribution of holes to prevent rupture and ensure transparency during EUV exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pellicle is sealed to create an enclosed space, then dust particles are prevented from entering, but pressure difference causes the pellicle to rupture
Solution Approach 1:
The frame is designed with a plurality of holes that allow pressure equalization between the enclosed space and the external environment. This porous structure prevents pressure buildup that would otherwise cause pellicle rupture while maintaining dust exclusion through the enclosed space configuration
Solution Approach 2:
The frame acts as an intermediary structure between the pellicle and the external environment. It provides mounting support for the pellicle while incorporating holes to mediate pressure equalization, thus protecting the pellicle from pressure-induced rupture
2Object-affected harmful factors
If the pellicle is mounted over the reticle, then the reticle is protected from dust, but trapped air causes pressure buildup and potential rupture
Solution Approach 1:
The frame incorporates a plurality of holes that function as a porous structure, allowing air and pressure to pass through. This enables the enclosed space between the pellicle and reticle to remain at equalized pressure with the external environment, preventing stress buildup that would compromise the pellicle
Solution Approach 2:
The frame is segmented into multiple sections with distributed holes rather than a continuous solid structure. This segmentation allows pressure equalization to occur at multiple points across the frame, effectively managing pressure distribution and preventing localized stress concentration
3Strength
If the frame is made solid to mount the pellicle, then the pellicle is securely held, but pressure cannot equalize and rupture occurs
Solution Approach 1:
The frame utilizes a porous design with multiple holes distributed across its structure. This allows the frame to maintain mechanical strength for secure pellicle mounting while simultaneously enabling pressure equalization between the enclosed space and external environment, adapting to both vacuum and atmospheric conditions
Solution Approach 2:
The frame combines structural integrity requirements with pressure equalization functionality through a composite design approach, integrating solid mounting sections with hollow or perforated pressure-equalizing sections
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 effectively maintains a stable pressure environment and prevents dust entry, enhancing the durability and transparency of the pellicle, thereby improving the EUV lithography process by ensuring consistent pellicle integrity across vacuum and atmospheric transitions.
Implementation Method 1
The plurality of holes produces a threshold percentage of opening in the frame to maintain an equalized pressure difference between a volume inside the enclosure and outside the enclosure
Data Source
AI summary
A lithography system includes an exposure device and a reticle structure disposed in the exposure device. The exposure device includes a reticle having patterned features, a membrane having a boarder section, and a frame disposed and forming an enclosure between the reticle and the membrane to encircle the patterned features. The frame includes a plurality of holes including at least one slit-shaped hole having one side formed by the reticle and three sides formed by the frame.