Split-Beam Pulse-Stretching Laser for Narrow Linewidth Lithography
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Solution Overview
Problem
The spectral linewidths of KrF and ArF excimer laser apparatuses are wide, leading to chromatic aberration and decreased resolution in semiconductor exposure, necessitating a line narrowing module to reduce spectral linewidth, which increases cost and space requirements.
Innovation Solution
A laser apparatus configuration with an oscillator, first and second amplifiers, pulse stretchers, and a beam combiner, which splits and combines laser beams to enhance pulse width and reduce speckle contrast, while optimizing energy distribution and reducing installation space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is added to narrow spectral linewidth, then chromatic aberration is reduced and resolution is improved, but device complexity and installation space increase
Solution Approach 1:
The patent extracts only the essential line-narrowing function from a traditional LNM and implements it through a simplified cavity design with selective mirrors, removing unnecessary complex components while maintaining the spectral narrowing effect
Solution Approach 2:
The patent changes the resonator cavity parameters (length, mirror reflectivity, gas pressure) to achieve spectral linewidth narrowing without requiring additional complex optical elements, thereby reducing device complexity while improving resolution
2Manufacturing precision
If a line narrowing module is added to narrow spectral linewidth, then chromatic aberration is reduced and resolution is improved, but installation space increases
Solution Approach 1:
The patent segments the laser system into modular components with the resonator cavity integrated into the existing laser structure, allowing the line-narrowing function to be achieved within the existing footprint rather than adding separate external modules
Solution Approach 2:
The patent merges the line-narrowing resonator cavity with the existing laser amplifier structure, combining multiple functions (laser generation, amplification, and spectral narrowing) into a single integrated unit that reduces overall installation space
3Manufacturing precision
If pulse width is stretched to reduce speckle contrast, then image quality is improved, but energy distribution becomes less concentrated
Solution Approach 1:
The patent changes the temporal parameters of the laser pulse through controlled stretching in the resonator, extending the pulse duration to reduce peak intensity and speckle contrast while maintaining total energy delivery for high-quality imaging
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 effectively narrows spectral linewidth, reduces speckle contrast, and stabilizes energy distribution, enhancing semiconductor manufacturing resolution without increasing peak intensity or power consumption.
Implementation Method 1
an oscillator configured to output seed light in a pulse form
Implementation Method 2
a first amplifier configured to amplify the seed light and to output first amplified light
Implementation Method 3
a first pulse stretcher configured to stretch a pulse width of the first amplified light
Implementation Method 4
a beam splitter configured to split the first amplified light having a stretched pulse width into first split light and second split light having energy smaller than that of the first split light
Implementation Method 5
a second amplifier configured to amplify a part of the second split light and to output second amplified light
Implementation Method 6
a second pulse stretcher configured to stretch a pulse width of the second amplified light
Implementation Method 7
a beam combiner configured to combine the first split light and the second amplified light having a stretched pulse width to output combined light
Data Source
AI summary
A laser apparatus includes an oscillator configured to output seed light in a pulse form, a first amplifier configured to amplify the seed light and to output first amplified light, a first pulse stretcher configured to stretch a pulse width of the first amplified light, a beam splitter configured to split the first amplified light having a stretched pulse width into first split light and second split light having energy smaller than that of the first split light, a second amplifier configured to amplify a part of the second split light and to output second amplified light, a second pulse stretcher configured to stretch a pulse width of the second amplified light, and a beam combiner configured to combine the first split light and the second amplified light having a stretched pulse width to output combined light.