Substrate Table Capillary Sealing for Immersion Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In immersion lithography, sealing around the edge of a substrate is challenging, leading to liquid leakage and gas trapped between the substrate and its support, which can cause imaging defects due to gas bubbles in the immersion liquid.
Innovation Solution
A substrate table with a capillary passage forming surface and a meniscus pinning feature that pins the liquid meniscus inwardly, combined with a channel for overpressure to apply a radial outward force on the liquid, preventing leakage and bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid is supplied onto the substrate to enable immersion lithography, then imaging precision is improved, but liquid leakage and gas bubble formation occur causing harmful factors
Solution Approach 1:
A liquid confinement member with a flexible or deformable wall is positioned between the substrate and the final element of the projection system. The wall can deform to accommodate the substrate and maintain sealing, preventing liquid leakage and gas bubble formation while enabling immersion lithography imaging
Solution Approach 2:
A liquid confinement member acts as an intermediary component between the substrate and the projection system. This mediator maintains the liquid environment for improved imaging while preventing liquid escape and gas bubble contamination through its sealing structure
2Loss of substance
If a liquid confinement system is used to supply liquid locally, then loss of substance is reduced, but device complexity increases
Solution Approach 1:
The liquid confinement member utilizes capillary forces and surface tension to automatically confine and supply liquid to the required area. The structure self-regulates liquid distribution without requiring complex external control systems, reducing device complexity while preventing liquid loss
Solution Approach 2:
The liquid confinement member employs capillary action (a hydraulic principle) to control liquid flow and confinement. By designing the wall structure with appropriate capillary dimensions, liquid is automatically confined and supplied without mechanical pumps or complex hydraulic control systems
3Productivity
If the substrate is scanned during exposure, then productivity is improved, but liquid turbulence occurs causing harmful factors
Solution Approach 1:
The flexible wall of the liquid confinement member can deform dynamically during substrate scanning to maintain liquid confinement and prevent turbulence. This flexibility allows the system to accommodate high-speed scanning while keeping liquid stable
Solution Approach 2:
The liquid confinement member is designed with dynamic characteristics, allowing its wall to adapt and maintain sealing during substrate movement. This dynamic response prevents liquid turbulence during scanning exposure, enabling high productivity without harmful liquid motion
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 seals the edge of the substrate, preventing liquid leakage and gas bubbles from forming in the immersion liquid, thereby improving imaging quality and reducing evaporation losses.
Implementation Method 1
a capillary passage forming surface configured to form a first side of a capillary passage when an object is on the table, a surface of the object forming a second side, opposite the first side, of the capillary passage
Implementation Method 2
a meniscus pinning feature positioned radially inwardly of the capillary passage forming surface, the meniscus pinning feature configured to pin, in use, a radially inward position of a meniscus of fluid in the capillary passage
Implementation Method 3
a channel configured such that an overpressure of gas in the channel is effective, in use, to apply a radially outward force on liquid in the capillary passage
Data Source
AI summary
A table is disclosed in which measures are taken to seal between the table and an edge of an object, in use, supported on the table. In particular, a capillary passage is formed between the object on the table and the table itself. A meniscus pinning feature and/or the presence of an overpressure at the radially inward side of the capillary passage holds the liquid in the passage and helps prevent it from advancing further radially inwardly. The features to perform this function may be associated with or formed in a member surrounding the object. The member may be thermally decoupled from a part of the table.