EUV Laser Wave Front Compensation via Deformable Mirror
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Solution Overview
Problem
High-power laser beams used in extreme ultraviolet light source devices experience wave front distortion due to thermal effects, leading to inefficient amplification and irradiation, resulting in reduced EUV radiation power.
Innovation Solution
An extreme ultraviolet light source device with a detection and compensation system that adjusts the direction and shape of the laser beam to a predetermined state using multiple compensation units and sensors, ensuring efficient amplification and irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power laser beam is used to generate EUV radiation, then EUV radiation power is improved, but wave front distortion occurs due to thermal effects
Solution Approach 1:
The patent applies preliminary action by measuring the wave front of the laser beam before it is input into the amplification area using a wave front sensor, and then correcting the measured wave front using a deformable mirror. This pre-correction prevents thermal distortion from degrading the beam quality before amplification, thereby maintaining stable wave front characteristics while enabling high-power EUV radiation generation.
2Productivity
If high-power laser beam is used, then amplification efficiency is improved, but thermal distortion changes the shape and direction of wave front
Solution Approach 1:
The patent implements feedback control by using a wave front sensor to continuously measure the actual wave front of the laser beam, comparing it with the desired wave front, and then using a deformable mirror to correct the deviations. This closed-loop feedback system ensures that thermal distortion does not degrade amplification efficiency while maintaining the required wave front shape for optimal performance.
Solution Approach 2:
The patent replaces traditional mechanical wave front correction methods with a deformable mirror that uses electro-active polymers or piezoelectric actuators to dynamically adjust the mirror surface shape. This substitution enables precise, rapid, and automated wave front correction in response to thermal distortion, maintaining amplification efficiency without mechanical complexity.
3Power
If high-power laser beam is used, then EUV radiation output is improved, but focusing performance deteriorates due to wave front change
Solution Approach 1:
The patent applies preliminary action by measuring the wave front before the laser beam enters the amplification area and correcting it using a deformable mirror. This pre-correction ensures that the beam maintains its intended focusing characteristics throughout the optical path, preventing thermal distortion from degrading focusing precision while enabling high-power EUV radiation output.
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
Stabilizes the output characteristics of the laser beam, maintaining high-power EUV radiation generation by compensating for wave front distortions, thereby improving the focusing performance and power of the EUV radiation.
Implementation Method 1
an LPP (Laser Produced Plasma: plasma produced by a laser) type light source, which generates a plasma by irradiating laser beam on a target material, and employs EUV radiation emitted from this plasma
Implementation Method 2
The use of such high-power laser beam causes various optical elements in the optical path to absorb radiation and thus become hot
Implementation Method 3
When high-power laser beam passes through a lens or a window, the shape and refractive index of the lens or window vary due to a heat-originated temperature increase, changing the wave front of laser beam
Data Source
AI summary
An EUV light source device properly compensates the wave front of laser beam which is changed by heat. A wave front compensator and a sensor are provided in an amplification system which amplifies laser beam. The sensor detects and outputs changes in the angle (direction) of laser beam and the curvature of the wave front thereof. A wave front compensation controller outputs a signal to the wave front compensator based on the measurement results from the sensor. The wave front compensator corrects the wave front of the laser beam to a predetermined wave front according to an instruction from the wave front compensation controller.