Air Pad Mounting for Photomask Stress Uniformity
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Solution Overview
Problem
In the semiconductor industry, the use of gel layers as buffer layers in pellicle mounting systems for photomasks leads to non-uniform stress distribution, causing distortion and shifting errors during lithography operations, and makes it difficult to predict and address damage to the gel layer, resulting in higher costs and defective devices.
Innovation Solution
The use of an air pad with a compartment filled with air, supported by pins, which distributes stress uniformly across the photomask and allows for easy inspection and adjustment of air pressure without disassembly, reducing the risk of damage and improving the uniformity of stress application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a gel layer is used as a buffer layer in the mounting plate, then the photomask can be pressed against the pellicle supporting stage, but the stress distribution becomes non-uniform causing distortion and shifting errors
Solution Approach 1:
The patent replaces the solid gel layer with an air-filled cushion (pneumatic buffer) that distributes stress uniformly across the photomask surface. The air cushion is contained within a mounting plate and allows for adjustable pressure to achieve uniform stress distribution without causing photomask distortion or shifting errors during pellicle mounting.
2Ease of operation
If a gel layer is used as a buffer layer, then stress can be applied to mount the pellicle, but damage to the gel layer is difficult to predict and address
Solution Approach 1:
The air cushion system allows operators to easily monitor and adjust the air pressure to ensure the mounting plate is properly inflated and functioning. This self-monitoring capability enables early detection of potential issues before they cause damage, and the system can be maintained by simply replacing or repressurizing the air cushion rather than dealing with degraded gel material.
3Ease of manufacture
If a gel layer is used, then the mounting plate can function as intended, but inspection and maintenance require disassembly increasing complexity
Solution Approach 1:
The air cushion is designed as a removable or accessible component within the mounting plate, allowing operators to inspect, deflate, replace, or repressurize the air cushion without completely disassembling the mounting plate structure. This pneumatic design simplifies maintenance procedures compared to sealed gel layers that require full disassembly for inspection.
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
This solution enhances the uniformity of stress distribution on the photomask, reduces the risk of damage to the buffer layer, and allows for regular inspection and maintenance, thereby minimizing the production of defective semiconductor devices due to photomask distortion.
Implementation Method 1
an air pad disposed between the first side and the second side, wherein the air pad comprises a compartment filled with air
Data Source
AI summary
The present disclosure provides an apparatus for mounting a pellicle to a photomask, including a presser, a pellicle stage facing the presser, and a flexible material layer between the presser and the pellicle stage, wherein the flexible material layer includes a compartment filled with gas.