Immersion Lithography Liquid Confinement Control
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Solution Overview
Problem
Immersion lithography apparatuses face defects such as trail defects due to liquid residue and exposure defects caused by bubbles, which reduce yield and require improved liquid confinement and management techniques.
Innovation Solution
The immersion lithography apparatus incorporates a liquid confinement structure with a series of openings for fluid flow, and a controller that predicts liquid loss during motion changes, adjusting fluid flow rates at the leading and trailing edges of the liquid confinement structure to minimize liquid loss and maintain immersion fluid containment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the support table moves quickly through the liquid confinement structure, then productivity is improved, but liquid loss increases causing defects
Solution Approach 1:
The controller predicts liquid loss based on pre-stored motion data and edge passage information before the actual motion occurs. This allows the system to prepare and adjust fluid flow rates in advance during the motion sequence, preventing liquid loss defects while maintaining high exposure speed.
Solution Approach 2:
The system uses feedback from the predicted edge passage events and motion data to dynamically adjust the fluid flow rates. The controller continuously monitors the support table position and adjusts the liquid confinement structure's fluid flow in response to predicted liquid loss conditions, resolving the contradiction between speed and liquid containment.
2Reliability
If the fluid flow rate is increased to prevent liquid loss, then reliability is improved, but device complexity increases
Solution Approach 1:
Instead of uniformly increasing fluid flow rates across the entire liquid confinement structure, the system applies differential fluid flow rates specifically at the leading and trailing edges where liquid loss is predicted. This localized control approach maintains reliability while avoiding unnecessary complexity in the overall fluid control system.
Solution Approach 2:
The fluid flow rates are made dynamic and adjustable based on real-time motion conditions and predicted edge passage events. The controller modifies fluid flow rates during the exposure sequence rather than maintaining static high flow rates, achieving reliable liquid confinement with simpler control logic.
3Manufacturing precision
If the liquid confinement structure is made more restrictive to prevent liquid loss, then manufacturing precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system automatically predicts liquid loss events and adjusts fluid flow rates without requiring manual intervention. The controller uses pre-stored motion data and real-time position information to self-regulate the liquid confinement, maintaining high manufacturing precision while improving ease of operation through automation.
Solution Approach 2:
The controller is pre-programmed with motion data and edge passage information, allowing it to anticipate and prepare for liquid loss conditions before they occur. This preliminary configuration enables the system to maintain precise liquid confinement automatically, reducing the operational burden on users.
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 effectively reduces the occurrence of trail and exposure defects by maintaining better control over the immersion liquid, enhancing the stability of the meniscus and reducing the risk of liquid loss during motion changes, thereby improving the yield and throughput of the lithography process.
Implementation Method 1
a liquid confinement structure configured to confine a liquid to an immersion space between the projection system and a surface of the object and/or the support table using a fluid flow into and/or out of the liquid confinement structure through a series of openings formed in the liquid confinement structure
Implementation Method 2
The liquid confinement structure may create or use a flow of gas, for example to help in controlling the flow and/or the position of the liquid in the immersion space. The flow of gas may help form the seal to confine the liquid to the immersion space.
Implementation Method 3
the controller adapted to: predict whether the liquid will be lost from the immersion space during at least one motion of the series of motions in which an edge of the immersion space passes over an edge of the object, and if liquid loss from the immersion space is predicted, to modify the fluid flow such that a first fluid flow rate into or out of an opening of the series of openings at the leading edge of the liquid confinement structure is different to a second fluid flow rate into or out of an opening of the series of openings at the trailing edge of the liquid confinement structure
Data Source
AI summary
An immersion lithography apparatus controller configured to control a positioner to move a support table to follow an exposure route and to control a liquid confinement structure, the controller configured to: predict whether liquid will be lost from an immersion space during at least one motion of the route in which an edge of the object passes under an edge of the immersion space, and if liquid loss from the immersion space is predicted, modify the fluid flow such that a first fluid flow rate into or out of an opening at a leading edge of the liquid confinement structure is different to a second fluid flow rate into or out of an opening at a trailing edge of the liquid confinement structure during the motion of predicted liquid loss or a motion of the route subsequent to the motion of predicted liquid loss.