Nonlinear Crystal Wavelength Conversion for Narrower Laser Linewidth
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Solution Overview
Problem
The existing KrF and ArF excimer laser apparatuses have wide spectrum line widths, leading to chromatic aberration and a decrease in resolving power in semiconductor exposure apparatuses. To mitigate this, a line narrowing module is used, but there is a need for a more efficient method to reduce spectrum line width and maintain the performance of the laser apparatuses.
Innovation Solution
A wavelength conversion apparatus utilizing a non-linear crystal is introduced, which includes a first non-linear crystal, a container, a crystal holding member, windows for light guidance, a heater for temperature control, and a battery and controller for power management. This apparatus performs wavelength conversion and is integrated into a solid-state laser system to enhance the spectral narrowing and reduce chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gas laser apparatus (KrF or ArF excimer laser) is used as the exposure light source, then high power output is achieved, but the spectrum line width becomes wide causing chromatic aberration and resolving power decrease
Solution Approach 1:
The gas laser apparatus is divided into two functional segments: a master oscillator that generates narrow-spectrum ultraviolet light and an amplifier that boosts the power while preserving the narrow spectrum. This segmentation allows the system to achieve both high power output and narrow spectrum line width, resolving the contradiction between power and resolving power.
Solution Approach 2:
A narrow-bandpass filter is introduced as an intermediary component between the laser source and the exposure system. This filter selectively transmits only the desired narrow wavelength range while blocking other wavelengths, thereby reducing chromatic aberration and improving resolving power while allowing the use of high-power gas laser apparatus.
2Manufacturing precision
If a line narrowing module including an etalon or grating is provided in the laser resonator, then the spectrum line width is narrowed, but the device complexity increases
Solution Approach 1:
The line narrowing function is extracted from the complex laser resonator system and implemented separately using a narrow-bandpass filter. This external filtering approach achieves spectrum narrowing without modifying the internal resonator structure, thereby maintaining simple device architecture while improving spectrum line width.
Solution Approach 2:
Instead of using complex optical elements like etalons or gratings that require precise mechanical adjustment, the patent employs a narrow-bandpass filter with fixed optical parameters optimized for the desired wavelength range. This parameter-based solution simplifies the device while achieving the required spectrum narrowing effect.
3Manufacturing precision
If the wavelength of light is shortened to improve resolving power, then chromatic aberration increases, but the productivity of semiconductor manufacturing decreases
Solution Approach 1:
The patent employs a tunable narrow-bandpass filter that can dynamically adjust its transmission wavelength range to match the specific requirements of different semiconductor manufacturing processes. This dynamic adaptability allows the system to maintain optimal resolving power while maximizing productivity by eliminating the need for repeated adjustments and reconfigurations.
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 proposed solution effectively narrows the spectrum line width, reducing chromatic aberration and improving the resolving power of the semiconductor exposure apparatuses. This leads to enhanced performance and reliability in electronic device manufacturing processes.
Implementation Method 1
a wavelength conversion apparatus that performs wavelength conversion of light through a non-linear crystal
Implementation Method 2
The first heater may be provided inside the container and configured to heat the first non-linear crystal
Data Source
AI summary
A wavelength conversion apparatus according to an aspect of the present disclosure is a wavelength conversion apparatus that performs wavelength conversion of light through a non-linear crystal and including a first non-linear crystal, a container in which the first non-linear crystal is housed, a crystal holding member provided inside the container for fixing the first non-linear crystal, a first window provided to the container for guiding light to the first non-linear crystal from outside of the container, a second window provided to the container for guiding light output from the first non-linear crystal to outside of the container, a first heater provided inside the container for heating the first non-linear crystal, a battery that supplies electric power to the first heater, and a first controller that controls electric power supply to the first heater.