Quantum Cascade Laser Timing Control for EUV Generation
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Solution Overview
Problem
In extreme ultraviolet (EUV) light generating systems, synchronizing the target reaching timing with the output timing of laser light of a predetermined wavelength from quantum cascade lasers (QCLs) is challenging due to variations in individual QCL characteristics, leading to potential misalignment of laser light amplification and target application.
Innovation Solution
A laser apparatus and measurement unit configuration that includes a quantum cascade laser, an amplifier, and a controller system to adjust delay times based on oscillation parameters such as current waveform and device temperature, ensuring the laser light reaches the predetermined wavelength at the aimed timing for effective amplification and target interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a quantum cascade laser is used to generate laser light for EUV light generation, then the laser light can be produced at the required wavelength, but the oscillation timing and wavelength stability become difficult to control due to individual QCL characteristic variations
Solution Approach 1:
The system measures the actual oscillation timing of the QCL and feeds this information back to the controller, which then adjusts the delay time to synchronize the laser light output with the target reaching timing. This closed-loop feedback mechanism compensates for individual QCL variations and ensures stable oscillation timing.
Solution Approach 2:
The system dynamically adjusts the delay time parameter based on measured QCL oscillation characteristics. By changing the delay time parameter in response to actual QCL performance, the system optimizes the synchronization between laser light generation and target arrival, resolving the timing stability issue.
2Productivity
If the laser light output timing is not precisely synchronized with target reaching timing, then the system operation is simplified, but the amplification efficiency and EUV light generation effectiveness are reduced
Solution Approach 1:
The measurement unit measures the actual oscillation timing and feeds this information back to the controller, which automatically adjusts the delay time. This feedback-based automatic adjustment achieves precise synchronization without requiring complex manual timing control systems.
Solution Approach 2:
The system uses its own measurement capability to automatically adjust its own timing parameters. The controller reads the measured oscillation timing and self-adjusts the delay time, eliminating the need for external complex timing control mechanisms.
3Reliability
If the delay time is fixed, then the system structure is simpler, but the laser light cannot be synchronized with target reaching timing when QCL characteristics vary
Solution Approach 1:
The delay time is changed from a fixed parameter to a dynamic parameter that automatically adjusts based on measured QCL oscillation timing. This dynamic adjustment mechanism ensures synchronization accuracy while using a relatively simple control structure that reads measurement results and modifies the delay time accordingly.
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 configuration ensures synchronized laser light output with the target reaching the plasma generation region, enhancing the efficiency of EUV light generation by aligning the laser light amplification with the target arrival, thereby improving the EUV light generation process.
Implementation Method 1
a quantum cascade laser (QCL) configured to output, on a basis of a supplied current, laser light at an oscillation start timing
Implementation Method 2
an amplifier configured to selectively amplify light of a predetermined wavelength to output the amplified laser light
Implementation Method 3
a plasma generation region into which a target is to be fed
Data Source
AI summary
A laser apparatus may include: a quantum cascade laser outputting, based on a supplied current, laser light at an oscillation start timing when a first delay time elapses from a current rising timing of the supplied current: an amplifier disposed in a laser light optical path, and selectively amplifying light of a predetermined wavelength to output the amplified laser light to a chamber including a plasma generation region into which a target is fed; and a laser controller controlling a third delay time, from an output timing of a laser output instruction to the current rising timing, to cause a laser light wavelength to be equal to the predetermined wavelength at an aimed timing when a second delay time elapses from the oscillation start timing, based on oscillation parameters including the first delay time, a supplied current waveform, and a device temperature of the quantum cascade laser.