Laser Spectrum Waveform Control for Exposure Chromatic Aberration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor exposure apparatuses, the wide spectrum line width of KrF and ArF excimer laser beams leads to chromatic aberration, reducing resolving power, which is not adequately addressed by conventional spectrum line narrowing methods.
Innovation Solution
A method and apparatus for controlling the spectrum waveform of a laser beam by acquiring longitudinal chromatic aberration and setting a target value for a spectrum evaluation value, using a processor to adjust the spectrum waveform, thereby minimizing chromatic aberration and improving resolving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module including an etalon or grating is provided in the laser resonator to narrow the spectrum line width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent changes the spectral parameters of the laser beam by adjusting the gain medium composition and operating conditions to achieve narrow spectrum line width without requiring additional line narrowing modules. This involves modifying the laser apparatus parameters to intrinsically produce the desired spectral characteristics.
2Manufacturing precision
If the wavelength of light is shortened to improve resolving power, then resolving power is improved, but chromatic aberration increases
Solution Approach 1:
The patent uses a dual-wavelength laser system operating at 193 nm and 248 nm to simultaneously address resolving power and chromatic aberration. By controlling the spectral composition and intensity ratio between these two wavelengths, the system achieves high resolving power while compensating for chromatic aberration effects in the projection lens.
Solution Approach 2:
The patent introduces asymmetric spectral composition by using two distinct wavelengths with different intensities. The 193 nm component provides high resolving power while the 248 nm component helps compensate for chromatic aberration, creating a balanced asymmetric spectrum that optimizes both parameters.
Data Source
AI summary
A control method for a spectrum waveform of a laser beam output from a laser apparatus to an exposure apparatus includes acquiring a longitudinal chromatic aberration of the exposure apparatus, setting a target value of an evaluation value of the spectrum waveform by using a relation between the longitudinal chromatic aberration and the evaluation value, and controlling the spectrum waveform by using the target value.