Raman Depth Profiling of Patterned Structures Using Temperature Control
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Solution Overview
Problem
Existing Raman spectroscopy methods struggle to accurately measure the spatial distribution of material properties within complex patterned structures, particularly in multi-layer structures, due to the integration of light from the entire illuminated volume, which compromises the ability to measure local properties and average integrated properties.
Innovation Solution
A novel Raman-based measurement technique that varies temperature conditions to control the absorption properties of the structure, affecting the penetration depth of the excitation beam and utilizing model-based processing to extract spatial profiles of material and geometric properties by analyzing temperature-dependent Raman scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Raman spectroscopy is used to measure material properties in patterned structures, then material properties such as composition, stress, and crystallinity can be detected, but the spatial distribution of these properties cannot be accurately measured due to integration of light from the entire illuminated volume
Solution Approach 1:
The patent segments the measurement problem by using multiple excitation wavelengths to probe different depths within the structure. Each wavelength provides information from a specific depth range, allowing the spatial distribution to be reconstructed by combining results from multiple segmented measurements rather than attempting to measure the entire volume simultaneously.
Solution Approach 2:
The patent adds the wavelength dimension to the measurement approach. By varying the excitation wavelength, the system accesses different penetration depths, effectively transforming a two-dimensional surface measurement into a three-dimensional volumetric measurement capability. This dimensional addition enables spatial distribution analysis without requiring complex mechanical scanning systems.
2Measurement precision
If the excitation beam penetrates deeper into the structure to access internal layers, then information from deeper regions can be obtained, but the signal from superficial regions is weakened or lost
Solution Approach 1:
The patent segments the depth range into multiple intervals, with each excitation wavelength optimized for a specific depth interval. This ensures that both surface and bulk regions are measured using wavelengths appropriate for their respective depth ranges, preventing information loss from either region.
Solution Approach 2:
The patent changes the excitation wavelength parameter to control penetration depth. By selecting different wavelengths from a broad spectrum source, the system adjusts the penetration depth to match the measurement requirement, ensuring optimal signal strength from the target region while maintaining the ability to access both surface and bulk information.
3Measurement precision
If multiple excitation wavelengths are used to access different depths, then spatial distribution information can be obtained, but the system complexity and data processing requirements increase significantly
Solution Approach 1:
The patent employs a broad spectrum light source that can serve multiple measurement functions by varying the excitation wavelength. This single multi-functional source replaces what would traditionally require multiple separate laser sources, reducing system complexity while maintaining the capability to access different depths and obtain spatial distribution information.
Solution Approach 2:
The patent creates a virtual representation of the spatial distribution through computational modeling. By measuring the Raman signal at multiple wavelengths and using forward modeling to simulate the expected signals, the system reconstructs the spatial profile through inverse modeling, replacing complex physical scanning mechanisms with computational analysis.
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
Enables accurate measurement of spatial distribution and average material properties within patterned structures, providing detailed information on composition, strain, and stress, even in complex geometries, by controlling temperature to alter absorption and penetration depth.
Implementation Method 1
Raman Spectroscopy works by probing vibrational modes of the sample, and the measured spectrum is usually comprised of a discrete set of peaks corresponding to the frequencies of these modes
Implementation Method 2
controlling temperature to alter absorption and penetration depth
Data Source
AI summary
A method and system are presented for use in measuring one or more characteristics of patterned structures. The method comprises: performing measurements on a patterned structure by illuminating the structure with exciting light to cause Raman scattering of one or more excited regions of the pattern structure, while applying a controlled change of at least temperature condition of the patterned structure, and detecting the Raman scattering, and generating corresponding measured data indicative of a temperature dependence of the detected Raman scattering; and analyzing the measured data and generating data indicative of spatial profile of one or more properties of the patterned structure.