Dual Frequency Comb Ellipsometer for High-Throughput Metrology
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Solution Overview
Problem
Traditional Mueller Matrix Spectroscopic Ellipsometry (MMSE) techniques fail to meet the throughput and spot size requirements for characterizing complex and small semiconductor structures.
Innovation Solution
A measurement system utilizing dual frequency combs with different repetition rates, where one is frequency or phase-locked to the other, combined with coding optical elements that encode transfer matrix data into spatial, spectral, or temporal domains of images, enabling efficient generation of transfer matrix datasets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional Mueller Matrix Spectroscopic Ellipsometry (MMSE) techniques are used, then measurement capability is provided, but throughput and spot size requirements are not met
Solution Approach 1:
The patent segments the measurement process by using multiple frequency combs with different repetition rates to simultaneously measure different aspects of the sample's optical properties. This allows parallel processing of multiple measurement tasks, thereby increasing throughput while maintaining measurement precision through the dual-frequency comb approach.
Solution Approach 2:
The patent introduces an additional temporal dimension by using frequency combs with different repetition rates. This enables encoding of multiple transfer matrix elements into the temporal domain of the measured signal, allowing simultaneous extraction of multiple optical parameters without compromising measurement accuracy.
2Measurement precision
If traditional MMSE techniques are used, then measurement capability is provided, but spot size requirements are not met
Solution Approach 1:
The patent segments the illumination beam into multiple frequency components using dual frequency combs, allowing different spatial modes to be measured simultaneously. This enables the system to achieve both small spot size for high-resolution imaging and sufficient throughput by measuring multiple spatial frequencies at once.
Solution Approach 2:
The dual frequency comb system provides multi-functionality by simultaneously enabling spectrally resolved measurements, spatially resolved imaging, and polarization state analysis. This universal approach allows a single system to meet both small spot size requirements and throughput requirements without sacrificing either capability.
3Measurement precision
If coding optical elements are added to encode transfer matrix data, then measurement capability is enhanced, but device complexity increases
Solution Approach 1:
The patent introduces coding optical elements as intermediaries that modulate the frequency comb signal to encode transfer matrix elements. These elements act as mediators between the illumination source and the detector, enabling information encoding without requiring complex computational processing, thus enhancing measurement capability while managing device complexity.
Solution Approach 2:
The patent replaces complex mechanical modulation systems with optical coding elements that encode information directly in the optical domain. This substitution reduces mechanical complexity while enhancing measurement precision by enabling simultaneous encoding of multiple transfer matrix elements through optical phase and amplitude modulation.
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 allows for high-throughput, spatially and spectrally resolved transfer matrix measurements, overcoming the limitations of traditional MMSE techniques by providing stable and robust metrology data without the need for moving parts.
Implementation Method 1
a first frequency comb source configured to generate a first frequency comb; a second frequency comb source configured to generate a second frequency comb
Implementation Method 2
one or more coding optical elements including at least one of one or more optical retarders or one or more polarizers
Implementation Method 3
an imaging sub-system including one or more imaging lenses and a detector configured to generate a sequence of images of the sample
Data Source
AI summary
A measurement system may direct an illumination beam including at least one of a first frequency comb or a second frequency comb to a sample, and generate a sequence of images of the sample based on the first frequency comb and the second frequency comb. The system may include one or more coding optical elements to encode data associated with one or more transfer matrix elements into the sequence of images of the sample. The system may further generate a transfer matrix dataset including measurements of at least one of the one or more transfer matrix elements associated with the sample based on at least one of spectral, spatial, or temporal analysis of the sequence of images, and generate one or more measurements of the sample based on the transfer matrix dataset.