EUV Laser Power Control for Lithography Thermal Stability
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Solution Overview
Problem
Existing EUV lithographic systems face high energy consumption and temperature fluctuations in optical elements due to large changes in laser output power, which can lead to system instability and damage.
Innovation Solution
A control system adjusts the laser output power to maintain a constant or slowly changing average power level, minimizing temperature variations in optical elements by controlling the laser operation based on exposure process data and timing, ensuring the power consumption is reduced while maintaining manageable temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser output power is increased to improve EUV radiation intensity, then the productivity and patterning capability are improved, but the temperature of optical elements increases substantially causing system instability and potential damage
Solution Approach 1:
The laser operates in periodic pulses synchronized with the substrate transfer and exposure cycle. The laser fires only during exposure intervals and remains off during substrate loading/unloading, creating a periodic operation pattern that reduces average power and temperature while maintaining required EUV intensity during exposure
Solution Approach 2:
The substrate is pre-positioned and the system is pre-prepared before laser exposure begins. By having the substrate ready and positioned in advance, the laser can operate at full power during exposure without needing to compensate for setup time, thus maintaining productivity while reducing total operation time and average temperature
2Stability of the object's composition
If the laser operates continuously to maintain constant EUV output, then the stability of EUV radiation is improved, but the energy consumption increases significantly
Solution Approach 1:
The laser operates in periodic pulses synchronized with the substrate transfer and exposure cycle. The laser fires only during exposure intervals and remains off during substrate loading/unloading, creating a periodic operation pattern that reduces average power and temperature while maintaining required EUV intensity during exposure
Solution Approach 2:
The control system monitors exposure timing and substrate position to dynamically adjust laser operation. By using feedback from the exposure process timing and substrate transfer status, the system optimizes laser firing intervals to maintain EUV stability during exposure while minimizing energy consumption during non-exposure periods
3Adaptability or versatility
If the laser output power varies rapidly to adapt to changing exposure requirements, then the adaptability to different exposure processes is improved, but the temperature fluctuations cause system trips and damage
Solution Approach 1:
The laser operates in periodic pulses synchronized with the substrate transfer and exposure cycle. The laser fires only during exposure intervals and remains off during substrate loading/unloading, creating a periodic operation pattern that reduces average power and temperature while maintaining required EUV intensity during exposure
Solution Approach 2:
The system changes operational parameters (laser power level, pulse timing, duty cycle) based on the specific exposure requirements. By adjusting these parameters within controlled ranges and rates, the system adapts to different exposure processes while maintaining temperature within safe operating limits
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 reduces overall power consumption and prevents substantial temperature fluctuations, enhancing the longevity and stability of optical elements by maintaining a stable average power level, thus preventing system trips and damage.
Implementation Method 1
A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 nm
Implementation Method 2
determine, in dependence on at least the timing data, control data for changing the instantaneous output power of the laser such that, during the intended exposure processes, an average output power of the laser is substantially maintained at a constant level, or changes at, or slower than, a pre-determined rate
Data Source
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AI summary
Disclosed herein is a lithographic apparatus comprising: an EUV source that comprises a laser; and a control system; wherein: the control system is configured to obtain timing data of intended exposure processes; and the control system is configured to determine, in dependence on at least the timing data, control data for changing the instantaneous output power of the laser such that, during the intended exposure processes, an average output power of the laser is substantially maintained at a constant level, or changes at, or slower than, a pre-determined rate.