Patterning Device Support Gas Flow Thermal Control
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in controlling the temperature of patterning devices, leading to image distortion due to thermal expansion and heating effects, which existing correction methods inadequately address, especially as tighter tolerances are required.
Innovation Solution
A system comprising a patterning device support with a movable component and a gas flow mechanism that supplies and recirculates gas across the surface of the patterning device to control its temperature, using helium gas for enhanced cooling and maintaining the temperature at or near 20°C, with adjustable characteristics to achieve desired thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correction methods (reticle alignment, magnification correction, feed forward systems, lens correction) are used to address patterning device expansion, then image distortion is partially corrected, but imaging errors due to heating of the air between the patterning device and lens element cannot be reduced
Solution Approach 1:
The gas flow system is activated before radiation exposure to pre-cool the air between the patterning device and lens element, preventing thermal expansion and density changes that would cause imaging errors during exposure
Solution Approach 2:
A gas flow (typically nitrogen or other inert gas) is introduced as an intermediary medium between the patterning device and the surrounding environment, creating a controlled thermal atmosphere that prevents air heating and convection currents during radiation exposure
2Device complexity
If the patterning device operates without active cooling, then the device structure remains simple, but thermal expansion causes image distortion and overlay errors
Solution Approach 1:
A gas flow system is implemented to cool the patterning device and surrounding air, using pneumatic delivery of cooled gas through nozzles or channels positioned near the patterning device to maintain thermal stability without complex mechanical cooling structures
Solution Approach 2:
The temperature of the gas flow is controlled to match or be slightly below the desired patterning device temperature, and the flow rate is adjusted to achieve optimal cooling effect while minimizing mechanical complexity of the cooling 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 effectively reduces thermal expansion and image distortion by actively managing the temperature of the patterning device, improving precision and accuracy in lithographic processes.
Implementation Method 1
a gas flow mechanism configured to supply a gas flow across a surface of the patterning device... The gas flow affects the temperature of the patterning device
Data Source
AI summary
A patterning device support for controlling a temperature of a patterning device can include a movable component. The movable component can include a gas inlet for supplying a gas flow across a surface of the patterning device and a gas outlet for extracting the gas flow. The patterning device support can also include a gas flow generator coupled to a duct, for recirculating the gas flow from the gas outlet to the gas inlet.