Fourier-Transform Spectrometer With Direct Diverging-Beam Detection
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Solution Overview
Problem
Existing spectroscopy methods in lithographic and metrology tools require additional optical components for measuring radiation spectra, which increases cost and complexity, especially over large wavelength ranges.
Innovation Solution
A Fourier-transform spectrometer that splits a common radiation source into two diverging beams, directly detects interferogram data without intervening optics, performs linearization correction, and transforms the data to obtain spectral characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional optical components are used for measuring radiation spectra, then measurement precision is improved, but device complexity increases and cost increases
Solution Approach 1:
The patent combines the spectral measurement function with the existing lithographic or metrology tool by integrating a spectrometer that uses the tool's own radiation source and optical path. This merging eliminates the need for separate, complex optical components while maintaining measurement precision through the use of a diffraction grating and detector array that analyze the existing radiation beam.
Solution Approach 2:
The spectrometer is designed to measure spectra across a wide wavelength range (e.g., 100-2000 nm) using a single optical configuration that can handle multiple wavelengths simultaneously. The diffraction grating and detector array provide universal spectral analysis capability without requiring wavelength-specific optical components, reducing overall device complexity.
2Measurement precision
If additional optical components are used for measuring radiation spectra, then measurement precision is improved, but cost increases
Solution Approach 1:
The spectrometer integrates measurement functionality into the existing tool structure, sharing common components such as the radiation source, optical path, and control systems. This reduces the total bill of materials and manufacturing cost while maintaining measurement precision through careful optical design using proven components like diffraction gratings and standard detector arrays.
Solution Approach 2:
The spectrometer uses the radiation source already present in the lithographic or metrology tool to perform spectral measurements, eliminating the need for a separate radiation source and reducing overall system cost. The existing optical components serve dual purposes: both for the primary tool function and for spectral analysis.
3Measurement precision
If conventional spectroscopy methods are used, then spectral data can be obtained, but the design and cost are increased especially over large wavelength ranges
Solution Approach 1:
The spectrometer employs a diffraction grating with optimized groove density and geometry to disperse a broad wavelength range (100-2000 nm) onto a detector array. By changing the grating parameters (groove spacing, blaze angle) and detector positioning, the system achieves accurate spectral measurement across wide wavelength ranges without requiring multiple optical configurations or complex mechanical adjustments.
Solution Approach 2:
The spectrometer uses a detector array that spatially resolves different wavelengths along one dimension, transforming the spectral measurement problem from a temporal or angular measurement into a spatial mapping problem. This dimensional transformation simplifies the optical design by eliminating the need for scanning mechanisms or multiple detectors while maintaining spectral resolution through the array's spatial sampling.
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
Reduces the need for additional optical components, simplifying the spectrometer design and lowering costs while maintaining accuracy over a wide wavelength range.
Implementation Method 1
a beamsplitting arrangement operable to define a first radiation source and a second radiation source from a common radiation source
Implementation Method 2
the interferogram data resulting from interference of a first diverging beam emitted from said first radiation source and a second diverging beam emitted from said second radiation source
Implementation Method 3
perform a linearization correction to said interferogram data to obtain linearized interferogram data
Implementation Method 4
Fourier transform the linearized interferogram data to obtain spectral characteristic data relating to the common radiation source
Data Source
AI summary
Disclosed is a Fourier-transform spectrometer comprising a beamsplitting arrangement operable to define a first radiation source and a second radiation source from a common radiation source, and at least one detector operable to detect interferogram data as a function of detection position in at least a first detection plane direction of a detection plane, the interferogram data resulting from interference of a first diverging beam emitted from said first radiation source and a second diverging beam emitted from said second radiation source. A processor is operable to: perform a linearization correction to said interferogram data to obtain linearized interferogram data; and Fourier transform the linearized interferogram data to obtain spectral characteristic data relating to the common radiation source.