Wavelength Selection Element for EUV Laser Stability
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Solution Overview
Problem
In LPP type EUV light generation systems, reflection light and spontaneous emission light can damage devices and output EUV light unstably, as they are amplified by the laser amplifier and strike the target material.
Innovation Solution
A wavelength selection element is disposed in the laser beam path, capable of changing its selection wavelength to transmit light at higher transmittance than other wavelengths, thereby suppressing reflection light and spontaneous emission light from entering sensitive components and striking the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a laser amplifier is used to amplify the pulse laser beam to generate high-power EUV light, then the EUV light output power is improved, but reflection light and spontaneous emission light are also amplified and can damage devices and destabilize EUV light output
Solution Approach 1:
The patent extracts and removes the harmful components (reflection light and spontaneous emission light) from the amplified laser beam using wavelength selection elements. By placing these elements in the light path after amplification, the system selectively transmits only the desired wavelength while blocking harmful wavelengths, thus protecting downstream devices and stabilizing EUV light output.
Solution Approach 2:
The patent introduces wavelength selection elements (such as etalons or gratings) as intermediary components between the laser amplifier and the target. These intermediaries act as filters that allow the desired laser wavelength to pass through while blocking amplified spontaneous emission and reflection light, thereby mediating between the high-power laser source and the vulnerable downstream components.
2Reliability
If the wavelength selection element is disposed in the light path to filter harmful light, then device protection and EUV light stability are improved, but the system complexity increases
Solution Approach 1:
The wavelength selection elements serve multiple functions simultaneously: they select the desired laser wavelength for transmission, block harmful reflection and spontaneous emission light, and protect downstream components. This multi-functionality reduces the need for separate protective components, thereby limiting the increase in system complexity.
Solution Approach 2:
The patent introduces wavelength selection elements (such as etalons or gratings) as intermediary components between the laser amplifier and the target. These intermediaries act as filters that allow the desired laser wavelength to pass through while blocking amplified spontaneous emission and reflection light, thereby mediating between the high-power laser source and the vulnerable downstream components.
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 prevents damage to devices and stabilizes EUV light output by attenuating reflection and spontaneous emission light, ensuring reliable operation of the EUV light generation system.
Implementation Method 1
a wavelength selection element disposed in the light path of the laser beam and configured to transmit light of a selection wavelength at higher transmittance than the transmittance of light of other wavelengths
Implementation Method 2
an amplifier disposed in a light path of the pulse laser beam
Implementation Method 3
The laser beam focusing optical system may be configured to focus the pulse laser beam inside the chamber
Implementation Method 4
a master oscillator configured to output a pulse laser beam
Data Source
AI summary
A laser apparatus may include a master oscillator configured to output a pulse laser beam, an amplifier disposed in a light path of the pulse laser beam, a wavelength selection element disposed in the light path of the pulse laser beam and configured to transmit light of a selection wavelength at higher transmittance than transmittance of light of other wavelengths, and a controller configured to change the selection wavelength of the wavelength selection element.