Patterning Device Cooling System for Lithography Overlay Accuracy
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Solution Overview
Problem
The heating of patterning devices in lithographic apparatuses causes mechanical deformation, leading to overlay issues between layers of exposed substrates due to uneven temperature variations during exposure, which existing cooling systems do not adequately address.
Innovation Solution
A patterning device cooling system that includes a thermal conditioner and a controller to regulate the cooling based on the amount of exposure radiation absorbed, controlling parameters such as exposure dose, radiation transmission, scanning speed, and exposure path length to maintain consistent temperature across different layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the patterning device is irradiated by exposure radiation, then the circuit pattern is transferred onto the substrate, but the patterning device heats up causing mechanical deformation and overlay issues
Solution Approach 1:
The cooling system is activated before exposure begins and maintains cooling throughout the exposure process. The controller receives information about the exposure process and adjusts cooling parameters in advance and during exposure to prevent temperature rise that would cause mechanical deformation and overlay errors
Solution Approach 2:
The controller receives information about the exposure process and uses this feedback to adjust cooling parameters dynamically. This closed-loop control ensures the patterning device temperature is maintained at optimal levels despite varying exposure conditions
2Manufacturing precision
If the patterning device is cooled during exposure, then temperature variations are reduced, but the complexity of the cooling system increases
Solution Approach 1:
The cooling device serves multiple functions: it cools the patterning device, removes absorbed radiation energy, and works in conjunction with the controller to provide adaptive temperature management. This multi-functionality justifies the added complexity by delivering comprehensive temperature control
Solution Approach 2:
The controller adjusts cooling parameters such as coolant flow rate, temperature, or pressure based on exposure conditions. By dynamically changing these parameters, the system achieves precise temperature control without requiring overly complex hardware architecture
3Manufacturing precision
If the cooling parameters are adjusted based on exposure radiation absorbed, then overlay penalty is reduced, but the control system complexity increases
Solution Approach 1:
The controller receives information about the exposure process including the amount of radiation absorbed by the patterning device, and uses this feedback to adjust cooling parameters. This feedback mechanism enables precise overlay consistency while keeping the control logic manageable through automated decision-making algorithms
4Manufacturing precision
If the patterning device expands due to heating, then the circuit pattern formation is affected, but adding cooling infrastructure increases device complexity
Solution Approach 1:
A cooling medium acts as an intermediary between the patterning device and the heat generated during exposure. The cooling device delivers this cooling medium to the patterning device, allowing heat removal without direct mechanical contact that would add complexity to the device structure
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 reduces the overlay penalty between layers by minimizing temperature variations in the patterning device, thereby improving the accuracy of circuit patterns formed on substrates without compromising throughput.
Implementation Method 1
a thermal conditioner configured to thermally condition the patterning device
Implementation Method 2
a thermal conditioner configured to thermally condition the patterning device
Implementation Method 3
Some of the energy from the radiation beam is absorbed by the patterning device, causing the patterning device to heat up
Data Source
AI summary
A patterning device cooling system for thermally conditioning a patterning device of a lithographic apparatus, wherein the patterning device in use, is being irradiated by exposure radiation, wherein the patterning device cooling system comprises: a thermal conditioner configured to thermally condition the patterning device; and a controller configured to control the thermal conditioner to thermally condition the patterning device dependent on an amount of the exposure radiation absorbed by the patterning device.