Embedded Defect Depth Binning via Multi-Angle Scattering
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Solution Overview
Problem
Determining the depth of embedded defects in multilayer film stacks is challenging due to the invasive and time-consuming nature of existing methods, which are often impractical for production samples.
Innovation Solution
A non-invasive inspection system using multiple optical channels with adjustable polarizers to collect scattering signals from a sample at different solid angles, comparing these signals to training data to determine defect depths, allowing for accurate depth determination of embedded defects without invasive techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive measurement techniques such as focused ion-beam (FIB) milling are used to accurately determine defect depths, then measurement precision is improved, but productivity deteriorates due to time-consuming processes and limitation to representative test samples only
Solution Approach 1:
The patent replaces the mechanical invasive FIB milling system with an optical scattering measurement system. The inspection system uses optical channels to collect scattering signals from defects in multilayer stacks, determining defect depths non-invasively through optical property analysis rather than physical material removal, thereby enabling high-speed production inspection.
Solution Approach 2:
The patent creates a virtual model of defect depth by comparing measured scattering signals with training data from representative samples. Instead of physically measuring each defect, the system uses scattering signal patterns to infer depth information, copying the depth measurement capability from trained reference data to production samples.
2Measurement precision
If multiple optical channels with different solid angles are used to collect scattering signals, then measurement precision of defect depth is improved, but device complexity increases
Solution Approach 1:
The patent adds the solid angle dimension to the optical measurement system by implementing multiple collection channels with different angular ranges. This dimensional expansion allows the system to capture scattering signal variations with respect to angle, providing additional information for accurate defect depth determination without requiring invasive physical sectioning.
3Measurement precision
If polarizers are added to control polarization of light in collection channels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the polarization parameter of the optical system by incorporating polarizers in the collection channels. This allows the system to measure scattering signal variations with respect to polarization state, providing additional discriminatory information for accurate defect depth determination while using standard optical components.
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 efficient and accurate depth determination of embedded defects in multilayer film stacks, reducing the need for invasive methods and facilitating defect analysis in production samples.
Implementation Method 1
a first collection channel including at least a first detector to collect light from the sample in response to the illumination beam
Implementation Method 2
a first polarizer to control a polarization of the light from the sample incident on the first detector
Data Source
AI summary
An inspection system may include an illumination source to generate an illumination beam, illumination optics to direct the illumination beam to a sample. The system may further include a first collection channel to collect light from the sample within a first range of solid angles and at a first selected polarization. The system may further include a second collection channel to collect light from the sample within a second angular range, the second range of solid angles and at a second selected polarization. The system may further include a controller to receive two or more scattering signals. The scattering signals may include signals from the first and second collection channels having selected polarizations. The controller may further determine depths of defects in the sample based on comparing the two or more scattering signals to training data including data from a training sample having known defects at known depths.