Immersion Lithography Sensor Thermal Path Design
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Solution Overview
Problem
In lithographic apparatuses, sensors that come into contact with immersion liquids generate heat, causing thermal disturbances that can affect the imaging process, leading to unwanted aberrations and reduced precision in device manufacturing.
Innovation Solution
A sensor design with a transducer that has a lower thermal resistance path to a temperature conditioning device than to the immersion liquid, ensuring that heat is efficiently managed and minimized in the immersion liquid, thereby reducing thermal disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is provided to measure properties of the projection beam at substrate level, then measurement capability is improved, but heat generation causes thermal disturbances that worsen imaging precision
Solution Approach 1:
The harmful thermal effect is extracted and isolated from the imaging path by providing a dedicated heat flow path that diverts heat away from the immersion liquid and substrate, separating the thermal management function from the optical measurement function
Solution Approach 2:
A thermal management component acts as an intermediary between the sensor and the immersion liquid, providing a controlled heat flow path that prevents direct thermal coupling while allowing the sensor to operate
2Reliability
If the sensor operates continuously to maintain measurement accuracy, then measurement reliability is improved, but heat accumulation increases thermal disturbances
Solution Approach 1:
The thermal management system is activated before significant heat accumulation occurs, continuously managing heat flow during sensor operation to prevent thermal disturbances from reaching the immersion liquid and substrate
3Measurement precision
If the sensor is positioned close to the substrate for accurate measurement, then measurement precision is improved, but thermal coupling to the immersion liquid increases
Solution Approach 1:
The thermal management function is segmented into a dedicated heat flow path that is spatially and functionally separated from the optical measurement path, allowing the sensor to be positioned close to the substrate while preventing thermal coupling to the immersion liquid through the thermal management component
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 design minimizes heat transfer to the immersion liquid, reducing thermal aberrations and maintaining imaging precision, thus enhancing the accuracy and throughput of the lithographic process.
Implementation Method 1
a first heat flow path between the transducer and the temperature conditioning device has a lower thermal resistance than a second heat flow path between the transducer and the immersion liquid
Data Source
AI summary
A sensor for use in lithographic apparatus of an immersion type and which, in use, comes into contact with the immersion liquid is arranged so that the thermal resistance of a first heat path from a transducer of the sensor to a temperature conditioning device is less than the thermal resistance of a second heat flow path from the transducer to the immersion liquid. Thus, heat flow is preferentially towards the temperature conditioning device and not the immersion liquid so that temperature-induced disturbance in the immersion liquid is reduced or minimized.