Excimer Laser Spectrum Evaluation for Stable Lithography Imaging
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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 leads to reduced resolution, which is not adequately addressed by traditional methods focusing solely on narrowing the spectral line width.
Innovation Solution
A laser device equipped with a spectrometer and processor to calculate a spectrum evaluation value by integrating the product of the estimation spectral waveform and a function of wavelength deviation, enabling comprehensive waveform evaluation beyond just spectral line width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectral line width, then chromatic aberration is reduced and resolution is improved, but the device complexity increases
Solution Approach 1:
The patent implements feedback control by measuring the actual spectral waveform with a spectrometer and adjusting the line narrowing module to achieve a target spectral waveform. This closed-loop system automatically maintains optimal spectral characteristics without manual intervention, resolving the contradiction by making the complex device self-regulating.
Solution Approach 2:
The patent changes the evaluation parameter from simple spectral line width to a comprehensive spectral waveform evaluation that considers the entire spectral distribution. This allows for more precise control of chromatic aberration by optimizing the actual spectral shape rather than just its width, improving resolution while providing better guidance for the line narrowing module adjustment.
2Manufacturing precision
If spectral line width is narrowed to reduce chromatic aberration, then imaging quality is improved, but exposure performance stability deteriorates due to insufficient consideration of spectral waveform shape
Solution Approach 1:
The patent fundamentally changes the evaluation parameter from spectral line width alone to spectral waveform evaluation that encompasses the entire spectral distribution shape. This comprehensive parameter better reflects the actual impact on chromatic aberration and exposure performance, enabling stabilization by maintaining consistent spectral waveform characteristics rather than just narrow line width.
Solution Approach 2:
The patent establishes feedback control that measures the actual spectral waveform and adjusts the line narrowing module to achieve a target spectral waveform. This ensures exposure performance stability by automatically compensating for variations in spectral shape, making the system robust against environmental changes and component variations.
3Ease of operation
If traditional spectral line width measurement is used, then measurement simplicity is maintained, but measurement precision deteriorates due to insufficient representation of actual spectral characteristics
Solution Approach 1:
The patent changes the measurement parameter from simple spectral line width to comprehensive spectral waveform evaluation. The spectral waveform evaluation calculates evaluation values based on the entire spectral distribution, providing much more precise characterization of the laser light's actual spectral characteristics and their impact on chromatic aberration and exposure performance.
Solution Approach 2:
The patent replaces simple width measurement with a computational approach that uses a spectrometer to capture the full spectral waveform and processes it through evaluation calculations. This substitution of direct measurement with computational evaluation provides higher precision while maintaining operational feasibility through automated processing.
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
Stabilizes exposure performance by considering the shape of the spectral waveform, ensuring consistent imaging quality despite variations in spectral line width and shape.
Implementation Method 1
a spectrometer configured to generate a measurement waveform from an interference pattern of laser light output from the laser device
Data Source
AI summary
A laser device connectable to an exposure apparatus includes a spectrometer configured to generate a measurement waveform from an interference pattern of laser light output from the laser device; and a processor configured to calculate a first spectral waveform indicating a relationship between a wavelength and a light intensity using the measurement waveform, calculate a representative waveform included in a wavelength range of the first spectral waveform, and calculate an evaluation value of the first spectral waveform using a first integration value obtained by integrating, over the wavelength range, a product of a function of a wavelength deviation from the representative wavelength and the light intensity.