Phase-Modulated Spectral Linewidth Control for Exposure Lasers
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Solution Overview
Problem
The spectral linewidths of KrF and ArF excimer laser beams are too wide, leading to chromatic aberration and reduced resolution in semiconductor exposure, necessitating a method to narrow the spectral linewidth without limiting the adjustment range.
Innovation Solution
A laser apparatus with a configuration that includes a first and second semiconductor laser, amplifiers, an optical phase modulator, and a wavelength conversion system, adjusts the timing and spectrum of pulse laser beams through modulation signals to achieve a non-Gaussian shape and wider spectral linewidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberration is reduced and resolution is improved, but the adjustment range of spectral linewidth is limited
Solution Approach 1:
The patent applies dynamics by making the spectral linewidth adjustable rather than fixed. The optical phase modulator dynamically changes the phase of the laser beam during pulse formation, enabling continuous adjustment of spectral linewidth from narrow to wide ranges. This resolves the contradiction by transforming a static line narrowing module into a dynamic system that can adapt spectral characteristics.
Solution Approach 2:
The patent changes physical parameters by modulating the phase of the laser beam during the pulse formation process. By varying the phase modulation depth and timing, the spectral linewidth can be continuously adjusted. This parameter change approach allows the system to achieve both narrow linewidth (for reduced chromatic aberration) and wide linewidth (for increased adjustment range) as needed.
2Manufacturing precision
If the spectral linewidth is narrowed to reduce chromatic aberration, then resolution is improved, but the ability to adapt to different exposure requirements is reduced
Solution Approach 1:
The system dynamically adjusts spectral linewidth during pulse formation using phase modulation. This allows the laser to adapt to different exposure requirements by changing spectral characteristics in real-time, while maintaining the ability to achieve narrow linewidth when high resolution is needed.
Solution Approach 2:
By changing the phase modulation parameters during pulse formation, the system can adapt spectral linewidth to match different exposure requirements. This parameter flexibility enables the laser to optimize performance for various semiconductor manufacturing tasks while maintaining high resolution capability.
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 method stabilizes and widens the spectral linewidth, improving resolution and reducing chromatic aberration, enabling effective semiconductor manufacturing.
Implementation Method 1
an optical phase modulator disposed in an optical path of the second continuous light between the second semiconductor laser and the third amplifier
Implementation Method 2
a wavelength conversion system configured to perform sum-frequency mixing of the second pulse laser beam and the third pulse laser beam for wavelength conversion and to output a fourth pulse laser beam
Data Source
AI summary
A spectral linewidth adjusting method includes: adjusting a timing of a first trigger signal for amplifying and converting a portion of a first pulse laser beam to a second pulse laser beam and/or a timing of a second trigger signal for amplifying and converting a portion of second continuous light to a third pulse laser beam and adjusting a spectrum of a fourth pulse laser beam obtained by performing sum-frequency mixing of the second and third pulse laser beams to a first spectrum in a non-Gaussian shape; and modulating a wavelength of the second continuous light within time corresponding to one pulse of the third pulse laser beam and adjusting the spectrum of the fourth pulse laser beam to a second spectrum having a spectral linewidth wider than the first spectrum through generation of a modulation signal for supplying the modulation signal to an optical phase modulator.