Immersion Lens Meniscus Stabilization Using Vapor Alignment
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Solution Overview
Problem
Existing immersion lithography systems face challenges in maintaining the stability and reliability of the meniscus in the immersion lens due to low contact angles, which affect the stability and performance of the immersion lens.
Innovation Solution
The immersion lithographic system incorporates a vapor supply unit that aligns with the meniscus in a vertical direction to supply vapors with low surface tension, increasing the contact angle and stability of the meniscus, thereby enhancing the stability of the immersion lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid is supplied to form an immersion lens between the projection optical system and wafer, then resolution and depth of focus are improved through high refractive index, but the meniscus stability is reduced due to low contact angle with the wafer
Solution Approach 1:
The patent changes the physical-chemical parameters of the liquid by introducing vapors that reduce the surface tension of the immersion liquid. This parameter change increases the contact angle of the meniscus with the wafer, thereby improving meniscus stability while maintaining the high refractive index properties needed for resolution
Solution Approach 2:
The patent introduces a vapor phase as an intermediary substance that mediates between the immersion liquid and the environment. The vapor supplies low-surface-tension components that modify the liquid's surface properties, enabling the meniscus to achieve higher stability without compromising the optical performance
2Stability of the object's composition
If contact angle of meniscus is increased to improve stability, then meniscus stability is enhanced, but requires additional vapor supply mechanism increasing device complexity
Solution Approach 1:
The vapor supply unit is designed to perform multiple functions: it not only increases meniscus stability by modifying surface tension but also maintains optimal immersion liquid properties throughout the exposure process. This multi-functionality justifies the added device complexity by delivering multiple benefits from a single system
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 system achieves improved stability and reliability of the immersion lens by increasing the contact angle of the meniscus, leading to enhanced performance and stability of the immersion lithography process.
Implementation Method 1
The vapors supplied from the vapor supply unit may reduce a capillary number of the immersion lens
Implementation Method 2
The immersion lens may include a meniscus forming a contact angle of 90° or less with the wafer
Data Source
AI summary
An immersion lithographic system may include a wafer stage configured to support a wafer, a projection optical system on the wafer stage and configured to irradiate light toward the wafer, a liquid supply unit configured to supply a liquid between the wafer stage and the projection optical system to form an immersion lens through which the light is transmitted, and a vapor supply unit configured to supply vapors to the immersion lens. The immersion lens and the vapor supply unit may be aligned in a vertical direction.