Tunable Laser Ellipsometry for Thin-Film Characterization

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Solution Overview

Problem

Existing optical thin-film fabrication methods using broadband light sources face limitations in accuracy and sensitivity, particularly in measuring low average transmittance designs and optically thick fluids, due to low signal-to-noise ratios and impractical path lengths.

Innovation Solution

The use of tunable lasers, equipped with an optical parametric oscillator, enhances signal-to-noise ratios and allows for in-situ spectroscopic measurements by adjusting the output wavelength, enabling more accurate characterization of optical thin-film layers and determining characteristics of fluids with higher precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If broadband light sources are used in ellipsometry measurement systems, then the system can measure a broad spectrum of wavelengths, but the signal-to-noise ratio is low and measurement precision deteriorates

Engineering Contradiction:

Improvespectral coverageVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The broadband spectrum is segmented into multiple discrete wavelength regions, each measured sequentially using a tunable laser. This allows the system to achieve high signal-to-noise ratio at each wavelength point while still covering the full spectral range through systematic scanning across different wavelength segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The measurement system dynamically adjusts the laser wavelength throughout the measurement process. The tunable laser wavelength is scanned across the spectral range of interest, allowing the system to adaptively optimize measurements at different wavelengths while maintaining high precision through controlled dynamic tuning rather than static broadband illumination.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If broadband light sources are used, then the system can characterize optical properties across multiple wavelengths, but the path length becomes impractical and measurement accuracy decreases

Engineering Contradiction:

Improvemulti-wavelength characterizationVSAvoidpath length control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system employs dynamic wavelength tuning to optimize the optical path length for each measurement. By adjusting the laser wavelength according to the specific measurement requirements and sample properties, the system can maintain practical and controlled path lengths while achieving comprehensive multi-wavelength characterization capability.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If traditional light sources are used, then the system structure remains simple, but the ability to measure low transmittance designs is insufficient

Engineering Contradiction:

Improvesystem structureVSAvoidlow transmittance measurement capability

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system changes the fundamental parameter of light source from broadband continuous spectrum to tunable narrow-line laser spectrum. This parameter change enables high-intensity monochromatic radiation that can penetrate low transmittance samples, dramatically improving measurement capability for low transmittance designs while maintaining relatively simple system structure through the use of a single tunable laser source.

Inventive Principle:

Principle #35Parameter changes

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 enables the measurement of previously unmeasurable low transmittance ICE core designs and extends optical path lengths while providing more accurate and sensitive characterization of optical thin-films and fluids, improving the design and fabrication process.

Implementation Method 1

The use of tunable lasers, equipped with an optical parametric oscillator, enhances signal-to-noise ratios and allows for in-situ spectroscopic measurements by adjusting the output wavelength

Methodology Applied

Scientific EffectOptical parametric oscillation:

Implementation Method 2

a light source emitting electromagnetic radiation that reflects or refracts from a substance and optically interacts with an optical processing element

Methodology Applied

Scientific EffectOptical interaction (reflection/refraction): Reflection

Implementation Method 3

Ellipsometry is an optical measurement technique that may be used in the design and fabrication of optical processing elements, such as ICE cores or other optical thin films

Methodology Applied

Scientific EffectEllipsometry:

Data Source

PatentUS10145675B2Using tunable lasers in the design, manufacture, and implementation of integrated optical elements

Publication Date: 2018.12.04 HALLIBURTON ENERGY SERVICES INC

AI summary

Disclosed are systems and methods that use a tunable laser during optical thin-film fabrication. One disclosed system includes a tunable laser capable of generating electromagnetic radiation, one or more thin-film devices arranged to receive the electromagnetic radiation, each thin-film device including one or more optical layers deposited on a corresponding substrate and configured to generate optically interacted radiation upon receiving the electromagnetic radiation, and an optical transducer arranged to receive the optically interacted radiation from each of the one or more thin-film devices and configured to generate output signals corresponding to the optically interacted radiation received from each of the one or more thin-film devices.