Lithographic Actuation Coil Thermal Management
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Solution Overview
Problem
Lithographic apparatuses face challenges due to thermal cycles in actuation systems, leading to stress and strain on components, which can result in damage and require conservative designs to ensure longevity.
Innovation Solution
Incorporating a cooling system with a control unit to manage the temperature of coil assemblies in the actuation system, maintaining a predetermined temperature difference or range to minimize cyclic stress and reduce thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coils are used as force generating members in the actuation system, then positioning capability is achieved, but thermal cycles cause thermally induced stresses and strains that damage parts
Solution Approach 1:
The patent applies parameter changes by actively controlling the temperature of the coil assembly through a cooling system. The control unit adjusts cooling parameters to maintain the coil temperature within a range that prevents excessive thermal cycling, thereby reducing thermally induced stresses and strains while preserving the positioning capability of the coils.
Solution Approach 2:
The patent introduces a cooling system as an intermediary between the coil assembly and the thermal environment. This cooling system acts as a mediator that removes excess heat from the coils, preventing direct thermal damage to the coil assembly and surrounding parts while allowing the coils to continue generating force for positioning.
2Duration of action of stationary object
If large safety margins and conservative designs are used to account for fatigue, then component lifetime is extended, but actuation system performance is reduced
Solution Approach 1:
The patent converts the harmful effect of thermal cycling into a beneficial outcome by using the cooling system to create controlled thermal conditions. Instead of allowing uncontrolled thermal cycles that require conservative design margins, the cooling system actively manages temperature to extend component lifetime without sacrificing actuation performance.
3Duration of action of stationary object
If average loads of the actuation systems are kept relatively low, then component lifetime is extended, but positioning efficiency is reduced
Solution Approach 1:
The patent changes the thermal parameter of the actuation system by implementing active cooling control. This allows the system to maintain lower operating temperatures that extend component lifetime while enabling the coils to operate at optimal current levels for efficient positioning, rather than requiring reduced load operation.
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 approach extends the lifespan of actuation system components, allowing for less conservative designs and reduced thermal stress, thereby enhancing the reliability and efficiency of the lithographic apparatus.
Implementation Method 1
a cooling element interacting with the coil assembly for cooling the coil assembly
Implementation Method 2
the actuation system comprises a coil assembly including one or more coils as force generating members
Data Source
AI summary
The invention relates to a lithographic apparatus comprising: an actuation system for positioning an object; a control unit (CU) for controlling the actuation system; and a cooling system for cooling the actuation system, wherein the actuation system comprises a coil assembly (CA) including one or more coils (CO) as force generating members, wherein the cooling system comprises cooling element (CE) interacting with the coil assembly for cooling the coil assembly, and wherein the control unit is configured to control a temperature of the one or more coils to keep a magnitude of cyclic stress below a predetermined value.