HC-PCF Multi-Wavelength Source for Lithography Metrology
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Solution Overview
Problem
Existing metrology tools in lithographic apparatuses face challenges in generating high-quality, multiple wavelength radiation sources for accurate measurement and inspection of semiconductor structures, particularly in low-k1 lithography, where feature reproduction is difficult due to the classical resolution limit of lithographic apparatuses.
Innovation Solution
A hollow-core photonic crystal fiber (HC-PCF) is used to generate broadband radiation through seed-assisted cascaded four-wave mixing (FWM) to produce multiple wavelength radiation, which is suitable for metrology applications in semiconductor manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple wavelength radiation sources are used for metrology applications, then measurement accuracy and precision are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple wavelength generation capabilities into a single integrated device by merging a laser source, hollow-core photonic crystal fiber, and four-wave mixing nonlinear optical process into one compact system. This allows generation of multiple discrete wavelength bands (UV, visible, IR) simultaneously from a single device rather than requiring separate sources for each wavelength range.
Solution Approach 2:
The hollow-core photonic crystal fiber serves multiple functions: it acts as both the waveguide for the pump laser and the nonlinear optical medium for four-wave mixing. The single device structure provides universal capability to generate multiple discrete wavelength bands across different spectral regions (UV, visible, IR) that can be used for various metrology applications including scatterometry and spectroscopic ellipsometry.
2Manufacturing precision
If sophisticated fine-tuning steps are applied to lithographic projection apparatus, then pattern reproduction quality is improved, but process complexity increases
Solution Approach 1:
The patent provides preliminary action by generating multiple discrete wavelength bands in advance through the four-wave mixing process in the hollow-core fiber. These pre-generated wavelengths can then be directly used for various metrology measurements without requiring complex real-time tuning or adjustment of the lithographic apparatus during the measurement process.
3Manufacturing precision
If tight control loops are used for controlling lithographic apparatus stability, then pattern reproduction is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical control systems with an optical solution. Instead of using tight control loops with mechanical actuators to adjust the lithographic apparatus for different measurements, the system uses optical wavelength multiplexing where multiple wavelengths are generated simultaneously and can be selected or combined to perform various measurements without mechanical adjustments.
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 HC-PCF generates high-quality, broadband radiation capable of enhancing measurement accuracy and precision in metrology tools, improving the reproduction of patterns on substrates and enabling tighter process control in lithographic processes.
Implementation Method 1
A hollow-core photonic crystal fiber (HC-PCF) is used to generate broadband radiation through seed-assisted cascaded four-wave mixing (FWM) to produce multiple wavelength radiation
Data Source
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AI summary
A multiple wavelength light source device and associated method for generating output radiation comprising a plurality of discrete output wavelength bands. The multiple wavelength light source device comprises a pump radiation source arrangement configured to generate input radiation comprising at least a first frequency component and a second frequency component; and a hollow-core photonic crystal fiber configured to confine a working medium. The hollow-core photonic crystal fiber is configured to receive said input radiation and to generate said plurality of discrete output wavelength bands distributed over a wavelength range of interest via a seed-assisted cascaded four wave mixing (FWM) process in said working medium.