Nonlinear Optical System for High Frequency Metrology Radiation
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Solution Overview
Problem
Current metrology systems face challenges in generating high frequency radiation with sufficient power for accurate measurement of small features in lithographic processes, due to limitations in wavelength availability and the indirect nature of existing measurement techniques.
Innovation Solution
A system and method for providing output radiation, which involves spectrally broadening and temporally shortening a pulse of pump radiation after converting a portion of it into high frequency radiation, using a combination of nonlinear optical components, spectral broadening stages, and temporal compression stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pump radiation is converted into high frequency radiation via nonlinear optical processes, then the frequency/wavelength of the radiation is improved for metrology applications, but the power of the output radiation deteriorates due to conversion losses
Solution Approach 1:
The patent applies preliminary spectral broadening to the pump radiation before it undergoes nonlinear conversion to high frequency radiation. By broadening the spectrum of the pump radiation in advance, the system increases the bandwidth of the generated high frequency radiation, which improves measurement precision for metrology applications while managing the power conversion efficiency.
2Measurement precision
If the bandwidth of pump radiation is increased to improve output radiation properties, then the quality of output radiation is improved, but the temporal duration of radiation pulses worsens (increases)
Solution Approach 1:
The patent applies preliminary temporal compression to the pump radiation before nonlinear conversion. By compressing the pump pulses in time beforehand, the system achieves shorter output radiation pulses at the high frequency, which maintains good temporal characteristics despite the spectral broadening process.
Solution Approach 2:
The patent inverts the conventional sequence by applying temporal compression before spectral broadening, rather than the typical approach of broadening spectrum first. This inverted sequence of operations allows the system to maintain shorter pulse durations while achieving the desired broadband output radiation properties.
3Manufacturing precision
If sophisticated fine-tuning steps are applied to improve pattern reproduction at low k1, then the manufacturing precision is improved, but the device complexity worsens
Solution Approach 1:
The patent changes the fundamental parameter of radiation wavelength by generating high frequency radiation through nonlinear optical processes. This parameter change enables direct metrology at shorter wavelengths without requiring complex fine-tuning steps, thereby improving manufacturing precision while avoiding the associated device complexity.
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
This approach enhances the power of the output radiation, improves the conversion efficiency of high harmonic generation processes, and allows for more precise manipulation of radiation pulses, enabling better resolution and sensitivity in metrology applications.
Implementation Method 1
a first nonlinear optical component configured to convert a first portion of the pump radiation into converted radiation via a first nonlinear process
Implementation Method 2
a spectral broadening stage configured to broaden a radiation spectrum of the converted radiation, and to broaden a radiation spectrum of a second portion of the pump radiation
Implementation Method 3
a temporal compression stage configured to temporally shorten a pulse of the converted radiation, and to temporally shorten a pulse of the second portion of the pump radiation
Implementation Method 4
a second nonlinear optical component configured to receive the converted radiation and the second portion of the pump radiation, the second nonlinear optical component being further configured to generate output radiation via a second nonlinear process
Data Source
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AI summary
Described herein are systems and methods for providing output radiation, the systems and methods comprising broadening and/or temporally shortening radiation to produce the output radiation. The systems and methods may comprise broadening and/or temporally shortening two radiation beams having different wavelengths, for example a pump radiation beam and a converted (e.g. second harmonic) radiation beam.