Multilayer Sample Inspection via Fabry-Perot Interferometry
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Solution Overview
Problem
Conventional inspection systems are unable to correctly determine the composition and order of layers in multilayer samples during automated manufacturing processes, leading to potential manufacturing defects due to undetected orientation issues, such as upside-down samples.
Innovation Solution
A method and system utilizing a broadband light source, single mode optical fiber, beam splitter, and computer-controlled Fabry-Perot fringe analysis to determine the thicknesses and order of layers by measuring optical path differences and recording interferograms, allowing for accurate identification of layer compositions and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection systems are used to measure layer thickness, then thickness measurement capability is provided, but the ability to determine layer composition and order is lost
Solution Approach 1:
The patent transforms the inspection approach by changing the measurement parameters from simple thickness measurements to spectral reflectance measurements across multiple wavelengths. By analyzing how different materials reflect light at different wavelengths, the system can identify layer compositions and determine their order while maintaining thickness measurement capability
Solution Approach 2:
The patent introduces spectral analysis as an intermediary method between the inspection system and the multilayer sample. Instead of directly measuring physical thickness alone, the system uses spectral reflectance characteristics as an intermediary to infer both composition and structural information about the layers
2Ease of operation
If conventional inspection systems measure only thickness, then measurement simplicity is maintained, but detection of orientation defects (upside-down samples) becomes impossible
Solution Approach 1:
The patent applies the principle of analyzing optical properties (spectral reflectance) analogous to color changes. Different layer compositions and orientations produce distinct spectral signatures, allowing the system to detect upside-down samples by identifying unexpected spectral patterns that indicate incorrect layer orientation
3Device complexity
If conventional systems cannot identify layer compositions, then device complexity is reduced, but manufacturing precision deteriorates due to undetected defects
Solution Approach 1:
The patent replaces complex mechanical or chemical analysis methods with optical spectral analysis. By using light reflection characteristics across multiple wavelengths, the system achieves composition and orientation identification without requiring physical sampling or complex mechanical disassembly of the multilayer structure
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 correct identification of layer compositions and orientations, preventing manufacturing defects by accurately determining the thicknesses and order of layers, even in cases where samples are inadvertently turned upside down during processing.
Implementation Method 1
emitting, from a broadband light source, light over single mode optical fiber
Implementation Method 2
receiving, at a beam splitter, the light and splitting, at the beam splitter, the light into first and second portions
Implementation Method 3
spectrally analyzing the combined light using the system for analyzing Fabry-Perot fringes
Implementation Method 4
computer-controlled system for analyzing Fabry-Perot fringes
Data Source
AI summary
Inspecting a multilayer sample. In one example embodiment, a method may receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.