Immersion Lithography Substrate Surface Tension Gradient
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Solution Overview
Problem
Current immersion lithography techniques face challenges in achieving stability and precision due to variations in surface tension between the photoresist film and immersion liquid, leading to issues with bubble formation and liquid leakage, which complicates the process and makes it difficult to obtain a desirable surface tension.
Innovation Solution
A substrate with a photoresist film is designed to have a lower surface tension in the periphery region and a higher surface tension in the rest region, achieved through surface modification and film formation, using materials like fluororesin and silicon resin, to control interfacial tension and prevent liquid leakage while minimizing bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface tension of the photoresist film is low (wetting of the immersion liquid is poor), then immersion liquid hardly leaks out from the exposed area, but bubbles are easily produced in the immersion liquid
Solution Approach 1:
The patent applies local quality by creating different surface tension characteristics in different regions of the photoresist film. The periphery region has lower surface tension to prevent liquid leakage, while the central region maintains higher surface tension to prevent bubble formation. This spatial differentiation of surface properties allows simultaneous achievement of both requirements.
2Object-generated harmful factors
If the surface tension of the photoresist film is high (wetting of the immersion liquid is good), then bubbles are hardly produced, but the immersion liquid easily leaks out from the exposed area
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through regional surface tension differentiation. The central region maintains high surface tension to prevent bubbles, while the periphery region has reduced surface tension to prevent liquid leakage, allowing both requirements to be satisfied simultaneously.
3Ease of operation
If a third layer (mixed substance) is formed by mixing the immersion liquid and the gas substance, then the surface tension gradient pulling the immersion liquid is generated, but the desirable surface tension may be unobtainable due to various mixture ratios
Solution Approach 1:
The patent extracts the complex mixed substance approach and replaces it with a simpler surface modification method. Instead of creating a third layer by mixing immersion liquid and gas substance, the patent directly modifies the photoresist film surface to achieve the desired surface tension characteristics, eliminating the need for complex mixture ratio control.
Solution Approach 2:
The patent applies preliminary action by pre-modifying the photoresist film surface before immersion lithography to establish the desired surface tension distribution. This preliminary surface treatment eliminates the need for subsequent complex mixture formation and ratio control during the actual lithography process.
4Reliability
If the relationship between the surface tension of the photoresist film and the surface tension of the immersion liquid is adjusted afterward, then the immersion lithography process becomes complicated
Solution Approach 1:
The patent applies preliminary action by pre-establishing the desired surface tension relationship through surface modification of the photoresist film before immersion lithography. This eliminates the need for post-process adjustment and simplifies the overall process while ensuring stable surface tension characteristics.
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 configuration allows for stable and precise immersion lithography by preventing liquid leakage and bubble formation, simplifying the process and ensuring consistent surface tension, thereby improving the resolution and reliability of the immersion lithography process.
Implementation Method 1
a surface tension of the substrate in a periphery region is lower than that of the substrate in a rest region
Implementation Method 2
improving stability of surface tension (namely, interfacial tension) of the photoresist film in the immersion liquid
Data Source
AI summary
A substrate having a photoresist film, capable of easily performing immersion lithography with high precision and stability, is provided. A surface tension of the substrate in a periphery region is lower than that of the substrate in a rest region. Immersion liquid supplied onto the photoresist film hardly leaks out, and the bubbles hardly occur in the immersion liquid.