Line-Narrowing Gas Laser Wavelength Control for Stable Exposure
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Solution Overview
Problem
Chromatic aberration in semiconductor exposure apparatuses due to the large spectral line width of KrF and ArF excimer laser devices affects resolution, necessitating a line narrowing module to reduce spectral width, but existing wavelength control methods result in varying exposure results depending on the number of irradiation pulses, affecting the quality of electronic devices.
Innovation Solution
A line narrowing gas laser device with an actuator and processor that alternately performs different wavelength change patterns based on whether the number of irradiation pulses is even or odd, controlling the center wavelength to maintain consistent exposure quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectral width, then chromatic aberration is reduced and resolution is improved, but the spectral width narrowing causes the center wavelength to shift depending on the number of irradiation pulses, resulting in varying exposure results
Solution Approach 1:
The patent applies periodic action by alternately switching between a first wavelength change pattern and a second wavelength change pattern based on whether the number of irradiation pulses is even or odd. This periodic switching compensates for the cumulative wavelength shift caused by the line narrowing module, ensuring that the average wavelength remains substantially constant across different pulse numbers, thereby maintaining consistent exposure results while preserving the resolution benefits of spectral width narrowing.
2Measurement precision
If the spectral width is narrowed to reduce chromatic aberration, then resolution is improved, but the exposure results vary depending on the number of irradiation pulses
Solution Approach 1:
The patent implements feedback by monitoring the number of irradiation pulses and using this information to dynamically select the appropriate wavelength change pattern. The control system adjusts the wavelength in real-time based on the pulse count feedback, switching between patterns to compensate for cumulative shifts and maintain stable average wavelength, thereby ensuring consistent exposure results while maintaining narrow spectral width for high resolution.
3Reliability
If wavelength control is performed to maintain consistent exposure quality, then exposure result consistency is improved, but additional control mechanisms are required
Solution Approach 1:
The patent applies dynamics by making the wavelength control system adaptive and flexible. Instead of using a fixed wavelength control mechanism, the system dynamically switches between two different wavelength change patterns (first and second patterns) depending on whether the pulse number is even or odd. This dynamic adaptation allows the system to maintain consistent exposure results without requiring a complex multi-parameter control mechanism, as the switching logic is relatively simple.
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 ensures consistent exposure results by maintaining a stable average wavelength and integrated spectrum shape, enhancing the quality of electronic devices by minimizing variations due to pulse number-dependent aberrations.
Implementation Method 1
an actuator that changes a center wavelength of the pulse laser light
Data Source
AI summary
A line narrowing gas laser device includes an actuator changing a center wavelength of pulse laser light, and a processor controlling the actuator. The processor reads parameters including a number of irradiation pulses of pulse laser light to be radiated to one location of an irradiation receiving object, a shortest wavelength, and a longest wavelength; sets a first pattern with which the center wavelength is changed to approach the longest wavelength from the shortest wavelength and a second pattern with which the center wavelength is changed to approach the shortest wavelength from the longest wavelength such that at least one of the first pattern and the second pattern when the number of irradiation pulses is an even number is different from corresponding one when the number of irradiation pulses is an odd number; and controls the actuator so that the first pattern and the second pattern are alternately performed.