Seed Laser Wavelength Switching for Narrow-Linewidth Exposure Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor exposure apparatuses face challenges in maintaining resolution due to chromatic aberrations caused by wide spectral linewidths of KrF and ArF excimer laser light, which necessitate narrowing the spectral linewidth to prevent resolution degradation.
Innovation Solution
A laser apparatus is designed with a first and second seed laser, an optical switch, and a wavelength converter to sequentially select and pulse the laser light, converting the wavelengths to achieve narrow spectral linewidths, thereby reducing chromatic aberrations and improving resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module (etalon or grating) is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberrations are reduced and resolution is improved, but the device complexity increases
Solution Approach 1:
The patent changes the fundamental parameter of spectral linewidth by using two seed lasers with different wavelengths (e.g., 773.600 nm and 773.604 nm) instead of using a line narrowing module. This parameter change approach achieves narrow effective spectral linewidth without adding complex optical components like etalons or gratings to the resonator.
Solution Approach 2:
The patent segments the single laser source into two separate seed lasers, each operating at a slightly different wavelength. This segmentation allows independent control of each wavelength component and achieves spectral narrowing through selective wavelength conversion rather than through complex filtering mechanisms.
2Manufacturing precision
If KrF and ArF excimer laser apparatuses are used for exposure, then the wavelength is reduced to improve resolution, but chromatic aberrations occur due to wide spectral linewidth
Solution Approach 1:
The patent introduces an intermediary wavelength conversion process using nonlinear optical crystals. The seed lasers operate at a wavelength (e.g., 773.6 nm) that is then converted to the target exposure wavelength (e.g., 193.4 nm) through second harmonic generation. This intermediary approach allows precise wavelength control and narrow effective spectral linewidth, eliminating chromatic aberrations while achieving the desired short wavelength for high resolution.
3Object-generated harmful factors
If multiple seed lasers are used to achieve narrow spectral linewidth, then chromatic aberrations are reduced, but the device complexity increases
Solution Approach 1:
The patent designs the wavelength converter to handle multiple wavelengths from different seed lasers using the same nonlinear optical crystal and optical path. The system universally processes both wavelength components through a single conversion stage, achieving multi-wavelength operation without proportionally increasing device complexity. The optical switch and pulsing sections also serve multiple functions by controlling both seed lasers and the wavelength converter.
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
The solution enables high-speed switching between wavelengths, stabilizing pulse energy and improving image formation performance, even in thick photoresist films, by precisely controlling the optical switch and pulsing sections.
Implementation Method 1
a wavelength converter configured to output output laser light by using the pulse laser light, the wavelength converter outputting the output laser light having a first converted wavelength produced by wavelength conversion using the first oscillation wavelength, the wavelength converter outputting the output laser light having a second converted wavelength produced by wavelength conversion using the second oscillation wavelength
Data Source
AI summary
A laser apparatus includes a first seed laser outputting continuous-wave first seed laser light having a first wavelength, a second seed laser outputting continuous-wave second seed laser light having a second wavelength, an optical switch sequentially selecting the first seed laser light and the second seed laser light one at a time and outputting the selected seed laser light, a first pulsing section pulsing the selected laser light and outputting first pulse laser light, a wavelength converter outputting output laser light by using the first pulse laser light, and a processor controlling a timing of sequentially selecting the first seed laser light and the second seed laser light one at a time. The wavelength converter outputs the output laser light having a first converted wavelength produced using the first wavelength, and outputs the output laser light having a second converted wavelength produced using the second wavelength.