Multi-Wavelength Laser Apparatus for Semiconductor Exposure
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Solution Overview
Problem
The miniaturization and increased integration of semiconductor circuits require higher resolution in semiconductor exposure apparatuses, leading to demands for reduced wavelengths in exposure light sources, but gas laser apparatuses face issues with chromatic aberration due to wide spontaneous oscillation widths, necessitating the narrowing of spectral bandwidths to mitigate resolution drops.
Innovation Solution
A laser apparatus with a master oscillator capable of outputting laser beams having multiple wavelength peaks, a multi-wavelength oscillation control mechanism, and a spectrum detecting unit to control the energy of each wavelength peak, ensuring precise control of wavelengths and intensities to achieve a deeper depth of focus and improved exposure latitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gas laser apparatus is used as exposure light source, then ultraviolet laser beam can be outputted, but chromatic aberration occurs due to wide spontaneous oscillation widths
Solution Approach 1:
The patent segments the laser spectrum into multiple discrete wavelength peaks (first, second, third wavelength peaks) rather than using a continuous broad spectrum. This segmentation is achieved through the master oscillator system that generates multiple specific wavelengths, thereby reducing chromatic aberration while maintaining the ultraviolet output capability.
Solution Approach 2:
The patent changes the spectral parameters by controlling the intensity ratios between different wavelength peaks. Specifically, it sets the intensity ratio of the first and third wavelength peaks relative to the second wavelength peak to be 0.05 to 2.0, which optimizes the spectrum to reduce chromatic aberration while maintaining resolution.
2Manufacturing precision
If spectral bandwidth is narrowed using line narrowing element, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent merges the wavelength generation function into the master oscillator system itself, which directly outputs multiple discrete wavelength peaks without requiring external line narrowing elements. This integration eliminates the need for separate chromatic aberration correction components, thereby reducing device complexity while achieving the desired spectral control.
Solution Approach 2:
The master oscillator system is designed to simultaneously perform multiple functions: generating ultraviolet laser beams at multiple specific wavelengths, controlling intensity ratios between wavelengths, and providing a spectrum suitable for reducing chromatic aberration. This multi-functionality eliminates the need for separate line narrowing components.
3Manufacturing precision
If single wavelength laser is used, then chromatic aberration is minimized, but depth of focus and exposure latitude are limited
Solution Approach 1:
The patent transitions from a single-wavelength approach to a multi-wavelength approach by adding the spectral dimension. It outputs laser beams at three specific wavelengths (192.4 nm, 193.2 nm, and 194.0 nm) with controlled intensity ratios, thereby expanding the effective working range and improving both depth of focus and exposure latitude while maintaining chromatic aberration control.
Solution Approach 2:
The patent optimizes the spectral parameters by controlling the intensity ratios between different wavelength peaks. By setting the intensity ratio of the first and third wavelength peaks relative to the second wavelength peak to be 0.05 to 2.0, it achieves improved depth of focus and exposure latitude while maintaining acceptable chromatic aberration levels.
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 a deeper depth of focus and stabilized exposure latitude by controlling the peak intensities and wavelengths, specifically achieving the deepest depth of focus with a triple-peak spectral shape and intensity ratio of 0.95, enhancing the performance of semiconductor exposure processes.
Implementation Method 1
a master oscillator capable of outputting a laser beam that has a spectrum including at least three wavelength peaks
Implementation Method 2
a spectrum detecting unit that detects the spectrum of the above-mentioned laser beam
Data Source
AI summary
A laser apparatus includes a master oscillator capable of outputting a laser beam having a spectrum that includes at least three wavelength peaks, a multi-wavelength oscillation control mechanism capable of controlling energy of each of the wavelength peaks, a spectrum detecting unit that detects the spectrum of the above-mentioned laser beam, and a controller that controls the multi-wavelength oscillation control mechanism based on a detection result detected by the spectrum detecting unit.